5Min Intraday System Kommerzielles Mitglied Joed Nov 2006 2,183 Beiträge Ich bin mit dieser 5Min Intraday-Strategie mit großem Erfolg auf der EurUsd und GpbUsd. Drei Angebote max. pro Tag. Offene Position, wenn der Winkel des 50 Einfachen gleitenden Durchschnitts größer als 20Degrees ist und der Preis zurück in die Zone des 21 exponentiellen gleitenden Durchschnitts und der 10 exponentiellen gleitenden Durchschnitt zurückverfolgen. Set Stoploss bei 6 Pips plus Spread und Gewinn nehmen bei 8-10 Pips. Bewegen Sie den Stoploss, um zu brechen, sobald 6 Pips Verstärkung erhalten wird. Die Nutzung dieser Strategie erfolgt auf eigene Gefahr. Hoffe, jemand wird davon profitieren. Im Folgenden finden Sie einige wichtige Links zu Fragen und Informationen. Hierdurch arbeiten die wichtigsten Antworten. Danke an Golfer für die Kompilierung. Phillip Nel8217s 5min Intra-Day-System Zusammenfassung der Beiträge Termine: 01. Dezember 1997 bis 04. April 2008 Post-Nummern: Nr. 2761 bis 3450 (enthalten meine Regeln und Anhänge auf Golfer8217s Unterschrift) 1. Phillip8217s letzte Zusammenfassung seines 5min-Systems 2. Phillip8217s Beratung 3. Phillips8217 Trades: 4. Meine Regeln und Anhänge Anhang E 8211 TC-Muster auf MACD: Zeichnen Meine Kleine Widerstands - und Unterstützungslinien: Mkain8217s Referenzpost: Handelsplan und Geldmanagement: 5. Indikatoren zum Download 5min Vorlage und SMAangle-Indikator: Multipivot Und EJ CandleTime EA Smooth TC auf MACD Signal 2-Kerze Eintrag Setup Ausbreiten aus Moving Averages Typische EY bewegen: 7. 3 kleine Schwestern 8. Bullishbearish 3 Muster: 9. Ellipse Pullback Trades: 10. Triangle Trades 11. Kirche Muster Bildung: Erläuterung der Bildung der beiden Arten der Kirchenbildung: Beispiele und Diskussionen: Kommerzielles Mitglied Mitglied seit Nov 2006 2,183 Beiträge Einige weitere Beispiele Kommerzielles Mitglied Joed Nov 2006 2,183 Posts Einige weitere Beispiele Commercial Member Mitglied seit Nov 2006 2,183 Beiträge seit Mai 2006 Status: Least Qualified Poster 444 Beiträge Zitieren Phillip Nel Einige weitere Beispiele Wie beurteilen Sie die 20-Grad-Winkel Mitgliedschaft widerrufen Joined Dec 2005 2.300 Beiträge ok. Schaut gut auf einen starken Trend, aber was passiert auf der rechten Seite Ihres Diagramms diese Beispiele, die Sie geben, sind Kirschpflücken. Gleiche Hure. Different Dress Commercial Mitglied Mitglied seit Nov 2006 2,183 Beiträge Die 20 Degrees ist durch Sehkraft bestimmt. Es geht darum, mit dem Trend zu handeln, der stark ist, wenn der Winkel des 50MA stark in eine Richtung ist. Es geht nicht um den genauen Winkel. Man bekommt ein Gefühl für die Bewegung im Laufe der Zeit. Es ist wahr, dass die angegebenen Proben sehr wahr sind. Es soll die Erklärung erleichtern. Ich mache maximal drei Trades pro Tag. Nach zwei Siegen in einer Reihe (15-20 Pips) bin ich für den Tag fertig. Ein Sieg und ein Verlust machen mich auf mehr Zeit handeln. Zwei Verluste in einer Reihe und ich bin für den Tag. Ich werde schwierigere Beispiele posten. Der Hauptzweck ist es, einen starken 5min Trend durch den Winkel der 50MA zu bestimmen und dann geben Sie den Handel, wenn es zurück in die beiden anderen MAs Commercial Member Mitglied seit November 2006 2,183 Beiträge Dies war ein schwieriger Tag. Die violetten Bereiche sind die, wo der 50MA-Winkel zu flach für einen Trend und zu handeln. Trotzdem habe ich ein falsches und zwei richtige rades für den tag geschafft. Trade No1 war falsch und Handel 2 und 3 waren am Ende mit 8 Pips positiv. Es gab noch einige andere Trades, die mit dem Winkel der 50MA viel einfacher waren. Geben Sie der 50MA einige Zeit zu entwickeln und klar zu zeigen, seinen Winkel vor dem Eintritt auf ein Retracement in die 21EMA und 10EMA. Es gibt viele Chancen, hereinzukommen. Warten Sie, bis das gute Setup auftritt. Kommerzielles Mitglied Mitglied seit Nov 2006 2,183 Beiträge Ich habe drei Trades gemacht. Nein 1 war richtig, 2 war falsch und 3 war richtig am Ende 10pips für den Tag. Mitglied seit Sep 2006 Status: Chasing Trends 2.350 Beiträge Gute Methode Phillip. Nun meine zwei Pips. Kabel Preis immer haben eine Menge von whipsaw, so dass Sie wollen, um zu sehen, mindestens 50 sma für ur SL coz wird es sicherlich getroffen eine Menge von Zeiten. Ich habe ein System etwas ähnlich, wo ist die Verwendung von 55ema und 60 ema, um Trend Bias zu bestimmen. Von dort aus werde ich Preis-Action-Setups verwenden, um lange oder kurz zu gehen, abhängig von der ema-Projektion. Ziel 10-20 Pips pro Handel. Eurusd wird eine gute Option für diese Methode sein. Kommerzielles Mitglied Mitglied seit Nov 2006 2,183 Posts Sample. Sei sehr vorsichtig vor den Ankündigungen. Ich trage keine Nachrichten mit diesem System. Kommerzielles Mitglied Mitglied seit Nov 2006 2,183 Beiträge Ich treibe hauptsächlich die EurUsd aber wenn ich das richtige Setup in der GbpUsd sehe, gehe ich dafür. Kommerzielles Mitglied Joed Nov 2006 2,183 Beiträge Ich habe einen Handel gemacht, da es ein Sitter am Freitag war. Machte 15pips. Mitglied seit Oct 2005 Status: Straight Pippin 673 Beiträge Schaut gut aus. Ich werde testen Skills bezahlen die Rechnungen Joined Nov 2006 Status: Mitglied 44 Beiträge Ich fand, dass Ihr Trading System interessant und einfach ist. Tut mir leid für meine dumme Frage. Im Neuling hier habe ich nur ein paar Fragen zu deinem System Bitte korrigiere mich, wenn ich mich irre, die Regeln sind: - 50 SMA - 21 EMA - 10 EMA - Stoppen Sie den Verlust 6 Pips verbreiten - Profitieren Sie 8 - 10 Pips - Am besten auf USDEUR und GBPUSD - Offene Position bei 50 SMA Winkel mehr als 20 Grad. (Sorry, wenn mein englisch arm) und was machst du Männer von retrace int 21 EMA amp 10 EMA ist die Preislinie muss kreuzen oder schlagen die beiden EMA und 10 EMA - 50 SMA ist der Trend Indcator. Wenn 50 SMA Abwärtstrend. Wir öffnen verkaufen und visa versa - Wie lange haben Sie mit diesem System handeln? Und wie ist der Sieg Danke. Hoffnung youll Antwort. Mitglied seit Oct 2006 Status: Mitglied 296 Beiträge Nice method. Es wäre toll, wenn manche Filter vielleicht von der M15 für den Trend haben. Kommerzielles Mitglied Mitglied seit Nov 2006 2,183 Beiträge Es gab heute zwei Trades. Die Regeln sind wie folgt. 1. Der 50 Einfache gleitende Durchschnitt muss in einem starken Trend sein, der durch den Winkel identifiziert wird, in dem er sich befindet. 2. Warten Sie dann, bis der Preis in die Zone des 21EMA und des 10EMA zurückgezogen wird. 3. Geben Sie den Handel innerhalb dieser Zone ein. 4. Stoppen Sie auf 6 Pips plus Spread. 5. Stoppen Sie den Blitz, um zu brechen, nachdem 6 Pips Verstärkung eingeschaltet ist. 6. Nehmen Sie Profit 8-10 Pips. Average True Range Einleitung Die durchschnittliche True Range (ATR) ist ein Indikator, der von J. Welles Wilder, Jr. entwickelt wurde, der ihn zusammen mit einigen anderen Indikatoren (Parabolic SAR, RSI und der Directional Movement Concept) in seinem Buch, New Concepts in Technical Trading Systems im Jahr 1978. Die ATR wurde ursprünglich von Wilder entworfen, um die Volatilität von Commodities angemessen zu messen, ein Instrument, das typischerweise Lücken aufweist und Bewegungen beschränkt, die auftreten, wenn sich eine Ware nach oben oder unten öffnet Seine maximal zulässige Bewegung für die Sitzung. Heute kann die ATR eine der ältesten Indikatoren sein, die existieren, aber es ist weit davon entfernt, veraltet zu sein. Was ist sehr interessant an diesem Indikator ist seine universelle und adaptive Natur. Das ist, warum es anwendbar und beliebt bei guten Handelssystemen und wird mit einer Vielzahl von Instrumenten verwendet. Viele Handelssysteme nutzen die ATR als ein wesentliches Instrument zur Messung der Volatilität des Marktes. Die durchschnittliche True Range zeigt die Volatilität in einem bestimmten Instrument, aber es zeigt nicht die Preisrichtung an. Jeder Händler, der scharf auf die Gestaltung eines ausgezeichneten Handelssystems ist, sollte mit dem durchschnittlichen True Range vertraut sein und die vielen Möglichkeiten, wie es verwendet werden kann, um die Leistung eines jeden Handelssystems zu verbessern. Die ATR hat zahlreiche Funktionen und ihre allgemein anwendbar bei der Suche nach Handels-Setups, Einstiegspunkte, Stop-Loss-Levels und nehmen Profit-Ebenen mit vernünftigen Geld-Management-Technik. Definition von Begriffen amp Verwandte Konzepte Bevor wir vorgehen, definieren wir ein paar Begriffe, die wir häufig verwenden werden, während wir über die durchschnittliche True Range Average True Range (ATR) sprechen, ist ein Indikator, der die Volatilität misst. Es ist ein gleitender Durchschnitt des wahren Bereichs für einen bestimmten Zeitraum. Die Volatilität ist marktgerecht definiert. Ein aktiver Markt soll volatil sein, während ein inaktiver Markt als nicht-flüchtig betrachtet wird. Die Volatilität ist direkt proportional zum Bereich, also wenn der Bereich zunimmt, erhöht sich auch die. Wenn der Bereich abnimmt, ist auch die Volatilität des Instruments. Reichweite ist die Distanz, die der Preis pro Zeitschub bewegt. Es ist die Entfernung vom höchsten Preis zum niedrigsten Preis des Tages, also mit der Höhe von 1 bar oder Leuchter. Es wird berechnet, indem man den Unterschied zwischen dem Höhepunkt und dem Tiefpunkt nimmt. Allerdings, wenn die aktuelle Kerze ist ein Doji, wo der Preis nicht bewegt sich überhaupt, die reale Preisklasse ist eigentlich die Entfernung von der vorherigen Nähe der offenen Preis der Dogi (aktuelle Kerze). Auch wenn das Ende der vorherigen Kerze nicht innerhalb der aktuellen Kerze ist, beginnt die Reichweite vom Ende der vorherigen Kerze. Daraus folgt, dass die True Range (TR) die maximale Reichweite ist, die der Preis entweder während der aktuellen Kerze oder von der vorherigen Nähe des höchsten Punktes während der Kerze erreicht hat. True Range ist definiert als die größte Distanz der folgenden: A. Current High to the Current Low B. Zurück In der Nähe der aktuellen High C. Zurück In der Nähe der aktuellen Low Absolute Werte werden für die Berechnungen verwendet, um den Abstand zwischen den zwei Punkte. Das ist, weil das Ziel ist, die Distanz zu bekommen und nicht die Richtung. Der erste Bereich wird für die Berechnung des ersten True Range verwendet. Wir werden mehr darüber in einem anderen Abschnitt sprechen. Nach Wilder müssen Sie den Wert des Bereichs für eine Anzahl von Perioden berücksichtigen, damit es ein nützliches Werkzeug zur Messung der Volatilität ist. Aus diesem Grund muss ein Durchschnitt des wahren Bereichs über mehrere Perioden erreicht werden. Es muss eine ausreichende Anzahl von Zeiträumen verwendet werden, um eine ausreichende Stichprobengröße zu liefern, um eine genaue Angabe einer Instrumentenpreisbewegung zu erhalten. Er betrachtet 14 Takte als den besten Indikator für die Volatilität und nutzt ihn für sein Volatilitätssystem. Sie werden mehr über dieses System wissen, wie wir mitgehen. Hier ist, wie die ATR aussieht, wenn sie auf deinem Diagramm angewendet wird: CalculationFormula Um die durchschnittliche True Range (ATR) zu erhalten, wird der Durchschnitt der wahren Bereiche einer Anzahl von Perioden von Daten berechnet. Die Anzahl der Perioden beeinflusst, wie adaptiv die ATR für die jüngsten Veränderungen der Volatilität ist. Zum Beispiel macht ein kürzerer Durchschnitt von 10 bar die ATR mehr reaktiv auf die aktuelle Preisspanne und hat somit mehr Schwankungen im Vergleich zu einem längeren Durchschnitt von 20 bar, die eine stabilere ATR zeigen wird. Die ATR basiert in der Regel auf 14 Perioden und kann auf einer Intraday-, Tages-, Wochen - oder Monatsbasis berechnet werden. Wir verwenden 14 Perioden als unser Beispiel für die Berechnung. Die Berechnung des anfänglichen durchschnittlichen True Range (ATR) unterscheidet sich von dem Rest der ATRs. Bitte beachten Sie die folgende Tabelle für unsere Diskussion über die Berechnung: CH 8211 Aktuell High CL 8211 Aktuell Low PC 8211 Zurück Schließen TR 8211 True Range ATR 8211 Durchschnitt True Range Schritt 1: Berechnen Sie für True Range Wert für 14 Tage. Der erste True Range (TR) Wert wird aus nur 1 Periode erhalten und errechnet sich aus dem Abziehen des aktuellen Niedrigen auf den aktuellen Hoch. Der Rest der TRs wird einen Wert haben, der der größte unter den 3 Berechnungen wie definiert ist. TR für Tag 1 Strom High 8211 Strom Niedrig TR1 CH 8211 CL 1.36164 8211 1.36050 0.00113 TR für die Tage 2 bis 14 haben den größten Wert unter den folgenden: TR Current High (CH) 8211 Current Low (CL) TR Current High (CH) 8211 Zurück Schließen (PC) TR Strom Niedrig (CL) 8211 Zurück Schließen (PC) TR6 CH 8211 CL 1.35959 8211 1.35699 0.00260 TR9 CH 8211 PC 1.36190 8211 1.35490 0.00700 TR11 CL 8211 PC 1.36098 8211 1.36381 0.00283 Wir verwenden die Absolutwerte, da wie erwähnt Früher ist das Ziel dieser Berechnung, die Distanz unabhängig von der Richtung zu erhalten. Schritt 2: Berechnen Sie für den Initial Average True Range Wert. Die erste 14-tägige ATR ist der Durchschnitt der täglichen TR-Werte für die letzten 14 Tage. TR1 TR2 TR3 TR3 TR4 TR1 TR1 TR3 TR3 TR1 TR1 TR1 TR3 TR3 TR4 TR1 TR2 TR3 TR3 TR1 TR1 TR1 TR3 TR3 TR10 TR1 TR12 TR13 TR14 TR11 TR11 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR3 TR1 TR1 TR1 TR1 TR3 TR3 TR3 TR1 TR1 TR1 TR3 TR3 TR3 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR1 TR3 TR3 TR3 TR1 TR1 TR1 TR3 TR3 TR3 TR3 TR3 TR3 TR3 TR1 TR3 TR3 TR3 TR3 TR3 TR1 TR1 TR3 TR3 TR3 TR1 TR1 TR3 TR3 TR3 TR1 TR3 TR3 TR3 TR Bereichswert für den Rest der Tage. Um für die ATR für den Rest der Tage zu berechnen, wird nur die Information über die vorherige ATR gehalten. Multiplizieren Sie den vorherigen ATR mit 13, fügen Sie dann den aktuellen TR hinzu und teilen Sie ihn durch 14. Aktueller ATR (vorheriger ATR x 13) aktueller TR aktueller ATR (vorheriger ATR x 13) aktueller TR (0.00242x 13) 0.00397 Vorteile Es gibt 2 Hauptgründe dafür Machte die durchschnittliche True Rage (ATR) immer beliebter mit vielen Handelssystemen über die Jahrzehnte verwendet. Die ATR ist ein bemerkenswertes Maß für die Marktpreisbewegung, da sie über verschiedene finanzielle Wertpapiere hinweg genutzt werden kann und sich auch an die sich ändernde Marktvolatilität anpasst. Aus diesem Grund spielt es eine entscheidende Rolle bei der Einstellung Ihrer Stopps oder nehmen Profit-Levels. Nützliche über verschiedene finanzielle Wertpapiere Ein System, das nur für den Handel mit einem Markt verwendet werden kann, kann verwendet werden, um andere Märkte zu handeln, indem man einfach die Art und Weise, wie die Berechnungen ausgedrückt werden, verändert. Die Verwendung von Einheiten oder Vielfachen von ATR anstelle von endgültigen Werten wie Dollar, Punkten oder Pips kann jedes einfache System zu einem universellen Handelssystem machen. Eine der häufigsten Verwendungen der ATR ist die Einstellung der Stop-Loss-Ebene. Unten ist ein typisches Szenario, wie die ATR angewendet werden kann, um Ihren Halt für verschiedene Finanzinstrumente einzustellen. Stellen Sie sich vor, dass wir ein einfaches System verwenden, um mit zwei verschiedenen Instrumenten, einem Währungspaar (A) und einer Ware (B) zu handeln. Angesichts der Tatsache, dass, da ATR 0,0020 ist und Bs ATR 300 ist, würde der große Unterschied zwischen den Volatilitätsniveaus erfordern, dass wir 2 verschiedene Stop-Loss-Levels setzen. Zum Beispiel können unsere Stationen 0,0030 für A und 450 für B sein. Andererseits, wenn wir Werte in Einheiten oder Vielfachen von ATR verwenden, um unseren Stop-Loss für unser System zu setzen, benötigen wir nur einen Wert, um den Stop-Loss zu berechnen Ebene für beide Märkte. Wir können unseren Stop 1.5 ATRs ab dem Eintrittspreis einstellen. Da der Stop-Loss-Level noch 0,0030 betragen würde (berechnet von 1,5 x 0,0020) und der Bs-Stop-Level-Wert wäre auch bei 450 (berechnet von 1,5 x 300). Anpassungsfähig zum Ändern von Marktbedingungen Die Substitution von Einheiten oder Vielfachen von ATR auf den üblichen Dollar, Punkt, Pip oder welche Maßeinheiten, die in Ihrem System verwendet werden, können es auf lange Sicht ohne Reoptimierung trotz Änderungen der Preisbewegung oder Volatilität anwenden. Wir sind uns bewusst, dass sich die Marktbedingungen und damit die Preisbewegung oder die Volatilität ändern können und sich entweder abrupt oder allmählich ändern werden. Da sich die ATR im direkten Verhältnis zu Änderungen der Volatilität ändert, kann sie ganz einfach Ihren Stopp näher bringen oder weiter, um genügend Platz für die Preisbewegung zu erhalten, die normalerweise für diese bestimmte Volatilität erwartet wird. Es sei denn, der Markt hat sich in die Richtung geändert, du wirst nicht aufgehoben werden. Heres ein typisches Szenario, um diesen Punkt zu beweisen Wenn der Markt sich beruhigt und die ATR von A auf 0,0010 und B auf 150 wechselt, sind die 0,0030 Stopp für A und 450 Stopp für B jetzt zu weit, was dazu führt, dass du eine unnötig große Menge verlierst Von jedem einzelnen handel. Ähnlich, wenn der Markt extrem flüchtig wird und der ATR von A auf 0,0040 ansteigt und B auf 600 ansteigt, sind die 0,0030 Stopp für A und 450 für B jetzt zu nahe, was zu einem höheren Prozentsatz des Verlustes von Trades führt. Wir müssen unser System neu anpassen, um den aktuellen Marktbedingungen gerecht zu werden. Auf der anderen Seite, wenn wir Einheiten von ATR zu den Beträgen ersetzen, die wir ursprünglich als unser Stopp benutzten, würde unser System sich erheblich verbessern. Wenn sich die Volatilität ändert, würden sich unsere Stationen automatisch anpassen, um die Änderung zu berücksichtigen. Also, wenn der Markt sich beruhigt und die ATR von A auf 0,0010 und B auf 150 wechselt, wäre unser neuer Stop für A 0,0015 (berechnet von 1,5 x 0,0010) und unser Stopp für B wäre 225 (berechnet von 1,5 x 150 ). Ähnlich, wenn der Markt extrem flüchtig wird und ATR auf 40 Pips wechselt, wäre unser Stopp jetzt bei 60 Pips (1,5 x 40). Beachten Sie, dass der Stop-Loss-Level automatisch angepasst wird, auch wenn wir immer noch den gleichen Stop-Loss-Wert verwenden, der 1,5 ATR ist. Unser verbessertes System ist immer noch anwendbar und es besteht keine Notwendigkeit für eine Reoptimierung. Das ist das Wesen der Verwendung der ATR in jedem Handelssystem. Weil es sich dem Wandel anpassen kann und mit verschiedenen Märkten genutzt werden kann, ohne seinen Wert zu verändern, schneidet es deutlich ein großes Stück harter Arbeit ab, wenn man in verschiedene Märkte und die damit verbundenen Schwankungen der Volatilität schaut. Die meisten Systeme, die die ATR nutzen, gelten nicht nur in der Vergangenheit und in der Gegenwart, sondern auch in der Zukunft trotz aller Änderungen der Marktvolatilität. Interpretation der ATR Nun, da wir wissen, was die durchschnittliche True Rage (ATR) ist und wie es berechnet wird, müssen wir wissen, was die Werte der ATR bedeuten. Je nach Lesung kann die ATR in allen Aspekten des Handelsprozesses eingesetzt werden. Niedrige ATR-Lesung Eine niedrige Lesung von ATR zeigt einfach an, dass der Markt ruhig und weniger flüchtig ist. Das Volumen des Marktes ist leicht. Dies kann Folgendes bedeuten: 1. Der Markt reicht, wenn die ATR relativ niedrig ist. Es gibt nicht genug Volatilität, um den Markt in einem Aufwärtstrend oder einem Abwärtstrend zu bewegen. 2. Der Preis hat den Boden oder die Oberseite erreicht, der schließlich von der Preisumkehrung gefolgt wird. Schauen Sie sich das Bild unten an. Im ersten Abschnitt des Bildes oben, können Sie sehen, dass die ATR ist in der Regel niedrig und hat jetzt Peaks. Beachten Sie, dass der Markt gerade zu diesem Zeitpunkt reicht. In den übrigen Abschnitten wirst du sehen, dass sich ein Aufwärtstrend gebildet hat und jedes Mal, wenn die ATR die niedrigste Stufe erreicht, folgt eine Änderung der Preisrichtung. High ATR Reading Auf der anderen Seite zeigt eine erhöhte ATR einfach, dass der Markt sehr aktiv ist und sehr volatil ist. Dies deutet darauf hin, dass ein sehr stabiler Trend bevorsteht, denn es gibt genügend Bewegung auf dem Markt für den Preis, um sich in einem Aufwärtstrend oder einem Abwärtstrend zu bewegen. Die ATR-Gipfel, wenn eine der folgenden Situationen auftreten: 1. Während einer Rallye oder einer Periode der anhaltenden Preiserhöhung. 2. Während einer anhaltenden Periode des Preisrückgangs. Schauen Sie sich das Bild mit den unten markierten Gipfeln an. Wie Sie sehen können, steigt die ATR, wenn der Markt nach oben oder unten geht und es in der Regel spitzt, wenn eine anhaltende Bewegung aufgetreten ist. Wenn jedoch der Markt eine starke Bewegung in einer Richtung macht, die stärker ist als die normalen Schwankungen oben, wird davon ausgegangen, dass sich nun ein neuer Trend bildet (Ausbruch). Nun, da wir wissen, was die Lesungen der Durchschnitt True Range Mean, finden Sie heraus, wie diese Konzepte mit Logik in den verschiedenen Aspekten unseres Handels Einstieg, Stop Loss, Take Profit verwendet werden können. Wenn die ATR ihre niedrigsten Werte erreicht, folgt eine Änderung der Preisrichtung gewöhnlich. Heres, wie wir diese Informationen zu unserem Vorteil nutzen können. Wenn der Markt tendiert, geben Sie erst nach dem Preis zurück und kehrt zum allgemeinen Trend zurück. Hier werden wir kaufen, sobald ein Retracement beendet ist und der Preis weiter im Aufwärtstrend steigt. Umgekehrt werden wir nur verkaufen, sobald ein Retracement in einem Abwärtstrend beendet ist und der Preis weiter nach unten geht. Zum Beispiel wird ein 50 Perioden-Gleitender Durchschnitt (MA) verwendet, um den allgemeinen Trend zu identifizieren. Die aktuelle Schließung muss 2 ATRs oder mehr als die 50 MA, um sicherzustellen, dass die allgemeine Tendenz ist. Um sicherzustellen, dass wir in einem Retracement (Dip) sind, sollte die aktuelle Schließung 2 ATRs oder mehr unter dem Ende vor 5 Tagen sein. Sie werden wissen, wann das Dip beendet ist, wenn eine neue Kerze öffnet und 1 ATR über dem vorherigen Tiefstand erreicht. Der Preis ist jetzt wieder auf den allgemeinen Trend, und dies ist, wenn Sie den Kaufhandel eingeben. Das Gegenteil der oben genannten Bedingungen sind die Regeln für den Eintritt in einen Verkauf Handel. Der Markt wird in der Regel sehr volatil, wenn sich nun ein neuer Trend bildet. Dies wird als Ausbruch bezeichnet, und wir können die ATR-Werte verwenden, um es zu bestätigen. Da der Preis normalerweise nur bis zu einer Anzahl von ATRs nur erreicht, überschreitet dieser Wert, dass ein ungewöhnliches Phänomen auftritt, ein Ausbruch und damit der Beginn eines neuen Trends. Heres ein Beispiel. Angenommen, dass der Preis in der Regel steigt oder fällt 2 ATRs aus der vorherigen Nähe, werden Sie nur kaufen, wenn der Preis erreicht 3 ATRs höher aus dem vorherigen Schließen. Umgekehrt werden Sie nur verkaufen, wenn der Preis 3 ATRs niedriger als die vorherige Schließung erreicht. In den vorherigen Bildern werden Sie feststellen, dass ein niedriger ATR-Messwert immer von einem hohen Messwert gefolgt wird. Die ATR ist zyklisch in der Natur, zunehmend und abnehmend abwechselnd. Zu wissen, wann der Markt ruhig ist, ist wichtig, weil es bedeutet, dass die Volatilität bald zunehmen wird, was auf eine mögliche Handelseinrichtung hindeutet. Wenn wir unsere Signale verfeinern wollen, können wir mit einer Periode geringer Volatilität beginnen und auf eine Erhöhung der Volatilität warten, bevor wir den Handel betreten. Beachten Sie jedoch, dass die ATR nur die Volatilität und nicht die Richtung anzeigt. Sie werden entweder verkaufen oder kaufen abhängig von der Richtung des Trends. Manche Handelssysteme setzen nur Trades ein, nachdem der Preis den extremen Peak oder extremen Boden erreicht hat und sich umgekehrt hat. Hier werden Sie nur kaufen, nachdem der Markt einen deutlichen Preisrückgang erreicht hat, und Sie werden erst nach einer anhaltenden Periode des Preisanstiegs verkaufen. Sobald der Preis umgekehrt ist, warten die Händler darauf, dass sie eine Reihe von ATRs in die neue Richtung erreichen, bevor sie in den Handel gelangen. Je nach System variieren die Werte der Anzahl der ATRs und Perioden. Die durchschnittliche True Range spielt eine wichtige Rolle bei der Auswahl der Stop-Loss-Level in einem Handel. Es kann auch verwendet werden, um Ihre Haltestellen zu verfolgen. Ein gutes Beispiel wäre Chuck LeBeaus berühmten Chandelier Exit. Hier wird der Stop-Loss-Level in ATRs ausgedrückt, so dass er sich auch den veränderten Marktbedingungen anpasst. Der Stop-Loss-Level wird eine N-Nummer ATRs von der höchsten Highclose für einen Kaufhandel oder von der niedrigsten Lowclose wird für einen Verkauf Handel erreicht. Der Kronleuchterausgang ist so genannt, weil er von der Decke des Marktes nach unten hängt. Beachten Sie jedoch, dass die Bewegung der Kronleuchterausfahrt nur in eine Richtung ist. Es geht nur für einen Kaufhandel oder unten für einen Verkauf Handel. Die Ausstiegsregeln für Systeme, die den Chandelier Exit verwenden, können Sie Ihren Verlust beenden, wenn der Preis den höchsten Höchststand des Handels minus 3 ATRs erreicht (berechnet als Highest High 8211 3ATR) oder wenn der Preis den höchsten Abschluss erreicht, der während des Handels erreicht wurde, minus 3 ATRs (berechnet als Highest Close 8211 3ATR). Nehmen Sie Profit Die durchschnittliche wahre Reichweite wird nicht nur als Grundlage für die Stop-Loss-Ebene verwendet, sondern spielt auch eine wichtige Rolle bei der Einstellung der Take-Profit-Ebene. Unsere Diskussion über die Verwendung von Dollars, um den Wert des Stop-Loss-Levels auszudrücken, geht auf die gleiche Weise, wenn wir es als Anzahl von Perioden oder Pips ausdrücken. Lets gelten das gleiche Prinzip bei der Einstellung der nehmen Profit. Wir wissen, dass auch Backtests darauf hindeuten, dass ein bestimmter Wert wie 40 Pips der beste Take-Profit-Level ist, wird es nur für den Augenblick gelten und kann eine Reoptimierung benötigen, wenn sich die Marktbedingung ändert. Aber auch die Marktbedingungen ändern sich ständig und der Grad der Volatilität wird sich immer ändern. Wenn die Märkte ungewöhnlich ruhig sind, können wir unsere 40-Pip nicht erreichen. Auf der anderen Seite, wenn der Markt extrem volatil ist, können Sie nur 40 Pips nehmen, auch wenn Sie viel mehr als 40 Pips genommen haben könnte. Aus diesem Grund sind 40 Pips kein ideales Maß für unser Gewinnziel. Um ein stabileres System zu haben, brauchen wir ein Gewinnziel, das sich an Veränderungen der Volatilität anpassen kann. Dies kann erreicht werden, wenn wir unser Gewinnziel in Bezug auf ATR ausdrücken. Heres ein Beispiel. Angesichts der Tatsache, dass unsere Backtests zeigen, dass das beste Gewinnziel 4 ATRs ist, entspricht es 40 Pips unter normalen Marktbedingungen. Diesmal, wenn der Markt extrem leise ist, darf er nur 20 Pips entsprechen. Auf der anderen Seite, wenn der Markt sehr volatil wird, können 4 ATRs gleich 80 Pips sein. Es besteht keine Notwendigkeit für eine Reoptimierung, da sich das ATR-basierte Gewinnziel leicht an die veränderten Marktbedingungen anpasst. Bei der Verwendung der ATR basierte Gewinnziel und der Markt tendenziell extrem volatil ist, werden Ihre Gewinner größer sein als üblich, weil Ihr Ziel Gewinn hat sich mit der Erhöhung der Volatilität erhöht, auch wenn Sie den gleichen Prozentsatz der Gewinne Trades haben wird. Genau wie unser Beispiel früher, wenn der Markt extrem flüchtig wird, steigt der Wert unserer 4 ATR auf 80 Pips. Wir werden mit 40 weiteren Pips aussteigen, verglichen mit unserem üblichen Gewinnniveau unter normalen Marktbedingungen. Einstellen von angemessenen Stop-Loss und nehmen Profit-Ebenen sind wichtige Aspekte der Geld-Management, die kein Händler verpassen sollte. Lassen Sie mich Ihnen den Unterschied zeigen, dass die ATR machen kann, wenn sie in einem Handelssystem verwendet wird. Lets vergleichen 2 Systeme mit ähnlichen Regeln, aber mit verschiedenen Maßeinheiten. Schauen Sie sich das System 1 und das System 2 unten an. Die oben genannten Systeme sehen ähnlich aus. Wenn die aktuelle ATR 10 Pips ist, werden Sie eingegeben und mit den gleichen Preisen verlassen. Beide Systeme sind gleichermaßen wirksam, wenn nur die Marktbedingungen gleich bleiben. Leider ändert sich der Markt ständig und die Volatilität schwankt. Wenn das passiert, wird System 2 immer noch anwendbar sein, aber nicht System 1. Lassen Sie mich Ihnen zeigen, was ich meine8230 Angenommen, dass der Markt extrem flüchtig wird, dass die aktuelle ATR 20 Pips wird, ist die vorherige ATR, die 10 Pips wurde verdoppelt. Werfen Sie einen Blick auf die Tabelle unten, um ein besseres Verständnis des Szenarios zu haben. Wie Sie sehen können, bleibt der Eintrag für System 1 gleich. Mit dem Anstieg der Volatilität, werden Sie unangemessen in zu viel Trades eingegeben werden. Auf der anderen Seite gibt System 2 Ihnen nur die Einträge, die seit ihrer Eintragung aufgrund der erhöhten Volatilität zählen. Gleiches gilt für das Gewinnniveau. Mit System 1 werden Sie mit Ihrem Gewinn zu früh herausgenommen, und Sie erhalten nur 40 Pips pro Handel, auch wenn Sie 80 Pips verdient haben könnten. Mit System 2 können Sie größere Gewinne zu bekommen, weil die nehmen Profit-Ebene mit der Erhöhung der Volatilität erhöht. Für den Stop-Loss, System 1 wird nun nehmen Sie aus Ihrem Handel vorzeitig. Sie werden in und aus Trades mit Verlusten, die Sie nicht bekommen sollen. Im Gegensatz dazu ist der Stop-Loss-Level für System 2 viel weiter. Da die Volatilität zunimmt, wird der Stoppverlust entsprechend erhöht, um dem Preis genug Platz zu geben, um zurückzukehren und in seine ursprüngliche Richtung zurückzukehren. Da sich System 2 an die Veränderungen der Marktbedingungen anpasst, erreichen wir ein stabiles Winloss-Verhältnis. Darüber hinaus werden unsere Siegerhandels infolge des gestiegenen Gewinns durch die Erhöhung der Volatilität größer. Dies zeigt, dass System 2 eine signifikante Verbesserung von System 1 ist. Anwendung: ATR-gefiltertes SMA-System Sie haben nun gesehen, wie die richtige Verwendung der durchschnittlichen True Range ein einfaches Handelssystem erheblich verbessern kann. Lassen Sie mich Ihnen zeigen, wie ich die ATR verwende, um meine Eingaben zu filtern, den Verlust zu beenden und die Gewinnspannen für ein einfaches System mit 2 SMAs auszugleichen. Hier ist mein RTA-gefiltertes SMA-System. Währungspaar. EURUSD Ich benutze den 15-Minuten-Zeitrahmen, um nach dem ATR-Lesen zu suchen, bevor ich Handels-Setups findet. Ich benutze es auch, um meine Trades zu betreten. Ich benutze die 4 Stunden und 1 Stunde Zeitrahmen, um den allgemeinen Trend des Marktes zu bestätigen. 14 Periode Durchschnitt True Range (0,001 Level) 8 Periode Simple Moving Average (8 Periode SMA) 21 Periode Einfacher Moving Average (21 Periode SMA) Unten sind die Buy Trade Regeln für mein System. Das genaue Gegenteil gilt für Handelsregeln und wird nicht diskutiert. 1. Auf dem M15-Diagramm muss der 14 ATR 0,0010 oder weniger betragen, bevor er nach Signalen sucht. Dies deutet darauf hin, dass der Markt ruhig ist und ein möglicher Ausbruch stattfindet. Ich benutze nur die 0,001-Stufe, um als visuelles Signal zu dienen, dass die ATR im EURUSD-Diagramm einen niedrigen Wert erreicht hat. 2. Warten Sie, bis der Preis über dem 8 SMA und dem 8 SMA liegt, um über die 21 SMA in den H4, H1 und M15 zu überqueren. Ich tue dies, um sicherzustellen, dass ich in der passenden Tendenz bin, werde ich nur dann einen Kaufhandel betreten, wenn der Trend steigt. 3. Identifizieren Sie die letzten niedrigsten lowswing niedrig dann add 3 ATRs zum Schlusskurs dieser Kerze (Closing Price 3ATR). Warten Sie, bis der Preis über diesem Niveau liegt. Ich kann bestätigen, dass der Abwärtstrend zu einem Aufwärtstrend umgekehrt hat, wenn der Preis mehr als 3 ATRs von der niedrigsten Schließung bewegt. Ich benutze 3 ATRs, weil dies der empfohlene Multiplikator von Wilder ist. 4. Sobald Punkt 2 und Punkt 3 erfüllt sind, geben Sie einen Kaufhandel ein. 5. Setzen Sie den Stop-Loss 3 ATRs unter dem Eintrittspreis. Wenn sich der Preis gegen meine Gunst bewegt und 3 ATRs unter dem Eintrittspreis erreicht, gibt es eine größere Wahrscheinlichkeit, dass sich der Markt komplett gegen mich gewendet hat. Hier würde ich lieber meine Verluste kurz schneiden, bevor es aus der Hand kommt. 6. Beenden Sie am offenen der nächsten Kerze, wenn beide Bedingungen erfüllt sind: a. Die 8 SMA Kreuze unter dem 21 SMA. B. Preis kreuzt 3Arbeiten vom höchsten Ende Wenn die 8 SMA unter der 21 SMA kreuzt, kann es darauf hinweisen, dass der Preis jetzt zurückverfolgt oder umgekehrt wird. Ich benutze die ATR-Lesung, um dies zu bestätigen, also nur, wenn der Preis 3 ATRs vom höchsten Ende erreicht, nehme ich meinen Gewinn und schließe meinen Handel. Um eine bessere Idee zu bekommen, werfen Sie einen Blick auf einige Beispiele auf der nächsten Seite. Buy Trade Beispiel 1: Im obigen Bild können Sie sehen, dass ich auf der Suche nach dem Trade Setup entlang der blauen vertikalen Linie, wo die ATR ist unter 0,001 Ebene. Der Preis lag über den SMAs, und die 8 SMA gingen vollständig in die H4 und H1 am Ende der Kerze entlang der punktierten grünen vertikalen Linie. Das jüngste niedrigste Tief war bei 1.30899, das durch die blaue horizontale Linie angegeben wurde, und das ATR-Niveau war dann bei 0,0010, so dass ich 3 ATRs von dort berechnet habe, damit ich einen Kaufhandel betreten kann, wenn der Preis dieses Niveau übersteigt. Letzter Niedrigster Schließe 1.30899 3ATR Letzter Niedrigster Schließe 3 (0.0010) 1.30899 Ich trat einen Kaufhandel am offenen der Kerze ein, die durch die feste grüne Linie angegeben ist, dann setze ich meinen Stop-Loss Level 3 ATRs darunter. Kaufpreis Preis (offen von der nächsten Kerze) 1.31320 Stop Loss 1.31020 Eintrittspreis 8211 3 (ATR) 1.31320 8211 3 (0.0010) 1.31320 8211 0.00300 Später bemerkte ich, dass die 8 SMA unter der 21 SMA zu überqueren begann, also habe ich 3 berechnet ATRs von der höchsten Nähe zu bestätigen, dass der Trend jetzt umgekehrt und beendet den Handel, sobald der Preis dieses Niveau erreicht. Neueste Höchste Schliessen 1.33783 Höchste Schliessen 8211 3 (ATR) 1.33783 8211 3 (0.0014) 1.33783 8211 0.0042 ExitTake Profit 1.33417 Buy Trade Beispiel 2: In diesem Beispiel habe ich gerade den Prozeß der Überprüfung auf Signale wiederholt, als die ATR unter 0,001 ging. Ich wartete dann darauf, dass der Preis über den SMAs liegt und dass 8 SMA über 21 SMA liegen würde. Ich trat in den Handel ein, sobald der Preis 3 ATRs ab dem Ende des vorherigen Swing Low überschritt. Letzter Niedrigster Schluss 1.33068 3ATR Letzter Niedrigster Schluss 3 (0.0010) 1.33068 Ich setze dann meinen Stop-Loss Level 3 ATRs unter den Eintrittspreis. Kaufpreis Preis (offen von der nächsten Kerze) 1.33410 Eintrittspreis 8211 3 (ATR) 1.31320 8211 3 (0.0013) 1.31320 8211 0.0039 Als der Preis zurückging und die SMAs überquerten, berechnete ich für 3 ATRs aus der Nähe der höchsten Kerze und verließ die Position, wenn der Preis dieses Niveau erreicht hat. Höchste Schließe 1.34477 Höchste Schließe 8211 3 (ATR) 1.34477 8211 3 (0.0026) 1.34477 8211 0.0078 ExitTake Profit 1.33720 Sehen Sie sich dieses Video an, um zu sehen, wie ich die durchschnittliche True Range (ATR) zu meinem Vorteil in meinem einfachen Handelssystem verwende. KLICKEN SIE HIER, UM DAS VIDEO ANZUWENDEN KommentareNotes Die Verwendung des durchschnittlichen True Range bei der Ausprägung der Stop-Loss-Levels kann eine bestimmte Position zu höheren Risiken aussetzen, wenn die Volatilität stark zunimmt. Als solches kann es das maximale Risiko überschreiten, das durch unser Geldmanagement festgelegt wird. Es ist dann ratsam, einen Satz für Notsituationen in Dollars, Punkten oder Pips auszudrücken. Dies kann verwendet werden, wenn die Volatilität zunimmt und der Handel zu unseren Gunsten ist. Wir können auch die Losgröße reduzieren, um das Risiko zu reduzieren, aber dies nur, wenn die Volatilität zunimmt und der Handel gegen unsere Gunst geht. Um die erzielten Gewinne pro Handel zu maximieren, kannst du auch den Abstand vom Preis zu deinem nachlaufenden Stopp reduzieren, sobald du schon in einem stabilen Gewinn bist. Angenommen, dass Ihr nachlaufender Stopp ursprünglich auf 2 ATRs von der Höhe eingestellt ist und Ihr Profit stetig zunimmt, können Sie Ihren Stopp festziehen, indem Sie den Abstand zwischen Ihrem Highlow (für einen Buysell) und dem Stopp auf 1,5 ATR reduzieren. Schlussfolgerung In der Tat ist die durchschnittliche True Range (ATR) ein brillanter Volatilitätsindikator. Es identifiziert die Stärke der Preisbewegung oder Volatilität. Ein sehr volatiler Markt wird typischerweise von einem ruhigen Markt gefolgt, und weil die ATR identifiziert, wann die Volatilität zunimmt, kann sie helfen, den Ausbruch eines neuen Trends zu bestätigen. Obwohl die ATR nicht die Richtung des Marktes erzählen kann, ist es immer noch ein wichtiges Instrument, um logische Einträge, Gewinnziele und Stopps zu identifizieren. Abgesehen von den erwähnten kann die ATR sowohl in Verbindung mit anderen Indikatoren als auch als Teil eines Handelssystems verwendet werden, um zu helfen, Handelssignale zu filtern. Im Laufe der Jahrzehnte gelang es diesem einzigartigen Indikator, nicht nur zu überleben, sondern auch in vielen Handelssystemen populär zu sein, einfach aus diesen Gründen. Die ATR kann auf vielfältige Weise eingesetzt werden, um Ihr System trotz wechselnder Marktbedingungen anwendbar zu machen. Es macht auch Ihr System für verschiedene Finanzinstrumente geeignet. Ich hoffe, dass ich mit diesem Bericht die Bedeutung der durchschnittlichen True Range im Handel bei der ordnungsgemäßen Verwendung zeigen konnte. Ich schlage vor, Sie versuchen es aus und zwicken einige Einstellungen zu sehen, was am besten für Ihren Trading-Stil passt. Verbinden Sie uns bei Surefire Trading Challenge Sie brauchen nie zu kaufen oder zahlen für alles, um Teil unserer Community zu sein Der größte unabhängige Forex Trading Wettbewerb in der World4. Die körperliche Einstellung Die Menschen haben nie das Interesse verloren, herauszufinden, wie das Universum zusammengestellt wird, wie es funktioniert und wo sie in das kosmische Schema der Dinge passen. Die Entwicklung unseres Verständnisses der Architektur des Universums ist sicher nicht vollständig, aber wir haben große Fortschritte gemacht. Angesichts eines Universums, das aus Distanzen besteht, die zu groß sind, um zu erreichen und von Partikeln zu klein zu sehen und zu zahlreich zu zählen, ist es eine Hommage an die menschliche Intelligenz, dass wir so viel Fortschritte gemacht haben, wie wir es haben, wie die Dinge zusammenpassen . Alle Menschen sollten an dem Vergnügen teilnehmen, ihr Universum besser kennenzulernen. Wissenschaft für alle Amerikaner Einer der großen Erfolgsgeschichten der Wissenschaft ist die Vereinigung des physischen Universums. Es stellt sich heraus, dass alle natürlichen Gegenstände, Ereignisse und Prozesse so miteinander verbunden sind, dass nur relativ wenige Konzepte erforderlich sind, um sie zu verstehen. In gewisser Weise kompliziert diese Tatsache die Bemühungen, abzusehen, was die Schüler über das Make-up und die Struktur des Universums wissen sollten. Jede Art von Themen vernachlässigt unweigerlich viele Querverbindungen zwischen Themen. In der hier verwendeten Arrangement (und auch in der Wissenschaft für alle Amerikaner) erscheinen in verschiedenen Abschnitten Benchmarks, die sich mit der Schwerkraft, dem Elektromagnetismus und der Skala beschäftigen. Zum Beispiel 4A: Das Universum, 4B: Die Erde, 4F: Bewegung und 4G: Die Naturkräfte sind durch Ideen der Gravitationsanziehung und immensen Skalen von Distanz, Masse und Zeit eng verbunden. Und 4D: Struktur der Materie, 4E: Energietransformationen und 4G: Naturkräfte sind durch Ideen des Elektromagnetismus und der kleinsten Skalen von Distanz, Masse und Energie verbunden. Benchmarks für jeden Abschnitt sind mit anderen verbunden und sollten im Kontext der anderen gelesen werden. Das physische Universum ist ein Thema, in dem viele Ideen hohe Anforderungen an das Verständnis und die Vorstellungskraft der Schüler stellen. Studenten in der Grundschule können nur beginnen, Vorstellungen von Sternen und Materie zu bilden. Die drastisch unterschiedlichen Skalen von astronomischen und atomaren Phänomenen können erst über viele Jahre gelernt werden. Aber es ist wichtig, dass alle Schüler ein Gefühl für den Kontext von Ort, Zeit und physischen Interaktionen entwickeln, in denen ihr Leben auftritt. Studenten in den frühen Jahren sind besonders neugierig, wie die Welt funktioniert. Infolgedessen gibt es ein Dilemma, wann man Ideen in das Curriculum einführt. Auf der einen Seite ist es ratsam, die Schülerinnen und Schüler über Atome oder Galaxien zu unterrichten. Die meisten Schüler werden nur lernen, Tatsachen über sie zu rezitieren, mit wenig Verständnis. Auf der anderen Seite sind Diskussionen und Bilder über solche Unwägbarkeiten in den populären Medien üblich, und die Vermeidung von ihnen scheint unvernünftig zu sein. Das Curriculum kann sich auf Erfahrungen und Ideen konzentrieren, die für Kinder zugänglich sind, zum Beispiel, wie verschiedene andere Planeten von der Erde sind, oder die verschiedenen Arten von Materialien in der Natur gefunden. Und es kann Vorläufer zum eventuellen Verständnis aufbauen, wie z. B. beobachtbare Bewegungen am Himmel und beobachtbare Materialveränderungen. A. Das Universum In früheren Zeiten waren die Menschen überall sehr viel bewusst von den Sternen und waren mit ihnen vertraut, wie es nur wenige Menschen gibt. Damals wussten die Menschen die Muster der Sterne am Nachthimmel, die Regelmäßigkeit der Bewegungen der Sterne und wie diese Bewegungen mit den Jahreszeiten zusammenhingen. Sie nutzten ihr Wissen, um das Anpflanzen von Pflanzen zu planen und Boote zu navigieren. The constellations, along with the sun, the moon, and the quotwanderersquotmdashthe planetsmdashhave always figured in the efforts of people to explain themselves and their world through stories, myths, religions, and philosophies. For all of that, and for the sheer wonder the stars provoke on a clear, moonless night far from city lightsmdashawe that has inspired the expressive powers of poets, musicians, and artistsmdashscience is not needed. Why, then, insist that everyone become familiar with the heavens as portrayed by science Consider that in cities the night sky is no longer a familiar part of a persons neighborhood. Many people today live in circumstances that deprive them of the chance to see the sky often enough to become personally familiar with it. Fortunately, telescopes, photography, computers, and space probes make up the difference by revealing more of the cosmos in greater detail than ever before. Thus, science education can bring back the skymdashnot the same sky, but one that is richer and more varied than peoples eyes alone had ever led them to imagine. Finding our place in the cosmic scheme of things and how we got here is a task for the agesmdashpast, present, and future. The scientific effort to understand the universe is part of that enduring human imperative, and its successes are a tribute to human curiosity, resourcefulness, intelligence, and doggedness. If being educated means having an informed sense of time and place, then it is essential for a person to be familiar with the scientific aspects of the universe and know something of its origin and structure. In thinking about what students should learn about the heavens, at least three aspects of the current scientific view ought to be taken into account: (1) the composition of the cosmos and its scale of space and time (2) the principles on which the universe seems to operate and (3) how the modern view of the universe emerged. The benchmarks in this section deal primarily with composition and scale principles are dealt with in subsequent sections of the chapter, and some rudiments of the history of the scientific picture appear in Chapter 10: Historical Perspectives. Kindergarten through Grade 2 During these years, learning about objects in the sky should be entirely observational and qualitative, for the children are far from ready to understand the magnitudes involved or to make sense out of explanations. The priority is to get the students noticing and describing what the sky looks like to them at different times. They should, for example, observe how the moon appears to change its shape. But it is too soon to name all the moons phases and much too soon to explain them. Current Version of the Benchmarks Statements By the end of the 2nd grade, students should know that There are more stars in the sky than anyone can easily count, but they are not scattered evenly, and they are not all the same in brightness or color. 4AP1 The sun can be seen only in the daytime, but the moon can be seen sometimes at night and sometimes during the day. The sun, moon, and stars all appear to move slowly across the sky. 4AP2 The moon looks a little different every day but looks the same again about every four weeks. 4AP3 1993 Version of the Benchmarks Statements By the end of the 2nd grade, students should know that There are more stars in the sky than anyone can easily count, but they are not scattered evenly, and they are not all the same in brightness or color. 4AP1 The sun can be seen only in the daytime, but the moon can be seen sometimes at night and sometimes during the day. The sun, moon, and stars all appear to move slowly across the sky. 4AP2 The moon looks a little different every day, but looks the same again about every four weeks. 4AP3 Grades 3 through 5 Students should begin to develop an inventory of the variety of things in the universe. Planets can be shown to be different from stars in two essential ways8212their appearance and their motion. When a modest telescope or pair of binoculars is used instead of the naked eyes, stars only look brighter8212and more of them can be seen. The brighter planets, however, clearly are disks. (Not very large disks except in good-sized telescopes, but impressive enough after seeing a lot of stars.) The fixed patterns of stars should be made more explicit, although learning the constellation names is not important in itself. When students know that the star patterns stay the same as they move across the sky (and gradually shift with the seasons), they can then observe that the planets change their position against the pattern of stars. Once students have looked directly at the stars, moon, and planets, use can be made of photographs of planets and their moons and of various collections of stars to point out their variety of size, appearance, and motion. No particular educational value comes from memorizing their names or counting them, although some students will enjoy doing so. Nor should students invest much time in trying to get the scale of distances firmly in mind. As to numbers of stars in the universe, few children will have much of an idea of what a billion is thousands are enough of a challenge. (At this stage, a billion means more than a person could ever count one-at-a-time in an entire lifetime.) Students grasp of many of the ideas of the composition and magnitude of the universe has to grow slowly over time. Moreover, in spite of its common depiction, the sun-centered system seriously conflicts with common intuition. Students may need compelling reasons to really abandon their earth-centered views. Unfortunately, some of the best reasons are subtle and make sense only at a fairly high level of sophistication. Some ideas about light and sight are prerequisite to understanding astronomical phenomena. Children should learn early that a large light source at a great distance looks like a small light source that is much closer. This phenomenon should be observed directly (and, if possible, photographically) outside at night. How things are seen by their reflected light is a difficult concept for children at this age, but is probably necessary for them to learn before phases of the moon will make sense. Current Version of the Benchmarks Statements By the end of the 5th grade, students should know that The patterns of stars in the sky stay the same, although they appear to move across the sky nightly, and different stars can be seen in different seasons. 4AE1 Telescopes magnify the appearance of some distant objects in the sky, including the moon and the planets. The number of stars that can be seen through telescopes is dramatically greater than can be seen by the unaided eye. 4AE2 Planets change their positions against the background of stars. 4AE3 The earth is one of several planets that orbit the sun, and the moon orbits around the earth. 4AE4 Stars are like the sun, some being smaller and some larger, but so far away that they look like points of light. 4AE5 A large light source at a great distance looks like a small light source that is much closer. 4AE6 (BSL) 1993 Version of the Benchmarks Statements By the end of the 5th grade, students should know that The patterns of stars in the sky stay the same, although they appear to move across the sky nightly, and different stars can be seen in different seasons. 4AE1 Telescopes magnify the appearance of some distant objects in the sky, including the moon and the planets. The number of stars that can be seen through telescopes is dramatically greater than can be seen by the unaided eye. 4AE2 Planets change their positions against the background of stars. 4AE3 The earth is one of several planets that orbit the sun, and the moon orbits around the earth. 4AE4 Stars are like the sun, some being smaller and some larger, but so far away that they look like points of light. 4AE5 Grades 6 through 8 Students should add more detail to their picture of the universe, pay increasing attention to matters of scale, and back up their understanding with activities using a variety of astronomical tools. Student access to star finders, telescopes, computer simulations of planetary orbits, or a planetarium can be useful at this level. Figuring out and constructing models of size and distance8212for example, of the planets within the solar system8212is probably the most effective activity. Models with three dimensions are preferable to pictures and diagrams. Everyone should experience trying to fashion a physical model of the solar system in which the same scale is used for the sizes of the objects and the distances between them (as distinct from most illustrations, in which distances are underrepresented by a factor of 10 or more). Some experiences with how apparent positions of objects differ from different points of observation will make plausible the estimation of distances to the moon and sun. Finding distances by triangulation and scale drawings will help students to understand how the distances to the moon and sun were estimated and why the stars must be very much farther away. (The dependence of apparent size on distance can be used to pose the historically important puzzle that star patterns do not appear any larger from one season to the next, even though the earth swings a hundred million miles closer to them.) Using light years to express astronomical distances is not as straightforward as it seems. (Many adults think of light years as a measure of time.) Beginning with analogs such as automobile hours may help. Current Version of the Benchmarks Statements By the end of the 8th grade, students should know that The sun is a medium-sized star located near the edge of a disc-shaped galaxy of stars, part of which can be seen as a glowing band of light that spans the sky on a very clear night. 4AM1a The universe contains many billions of galaxies, and each galaxy contains many billions of stars. To the naked eye, even the closest of these galaxies is no more than a dim, fuzzy spot. 4AM1bc The sun is many thousands of times closer to the earth than any other star. Light from the sun takes a few minutes to reach the earth, but light from the next nearest star takes a few years to arrive. The trip to that star would take the fastest rocket thousands of years. 4AM2abc Some distant galaxies are so far away that their light takes several billion years to reach the earth. People on earth, therefore, see them as they were that long ago in the past. 4AM2de Nine planets of very different size, composition, and surface features move around the sun in nearly circular orbits. Some planets have a variety of moons and even flat rings of rock and ice particles orbiting around them. Some of these planets and moons show evidence of geologic activity. The earth is orbited by one moon, many artificial satellites, and debris. 4AM3 Many chunks of rock orbit the sun. Those that meet the earth glow and disintegrate from friction as they plunge through the atmosphereand sometimes impact the ground. Other chunks of rock mixed with ice have long, off-center orbits that carry them close to the sun, where the suns radiation (of light and particles) boils off frozen materials from their surfaces and pushes it into a long, illuminated tail. 4AM4 1993 Version of the Benchmarks Statements By the end of the 8th grade, students should know that The sun is a medium-sized star located near the edge of a disk-shaped galaxy of stars, part of which can be seen as a glowing band of light that spans the sky on a very clear night. The universe contains many billions of galaxies, and each galaxy contains many billions of stars. To the naked eye, even the closest of these galaxies is no more than a dim, fuzzy spot. 4AM1 The sun is many thousands of times closer to the earth than any other star. Light from the sun takes a few minutes to reach the earth, but light from the next nearest star takes a few years to arrive. The trip to that star would take the fastest rocket thousands of years. Some distant galaxies are so far away that their light takes several billion years to reach the earth. People on earth, therefore, see them as they were that long ago in the past. 4AM2 Nine planets of very different size, composition, and surface features move around the sun in nearly circular orbits. Some planets have a great variety of moons and even flat rings of rock and ice particles orbiting around them. Some of these planets and moons show evidence of geologic activity. The earth is orbited by one moon, many artificial satellites, and debris. 4AM3 Large numbers of chunks of rock orbit the sun. Some of those that the earth meets in its yearly orbit around the sun glow and disintegrate from friction as they plunge through the atmosphereand sometimes impact the ground. Other chunks of rocks mixed with ice have long, off-center orbits that carry them close to the sun, where the suns radiation (of light and particles) boils off frozen material from their surfaces and pushes it into a long, illuminated tail. 4AM4 Grades 9 through 12 This is the time for all of the pieces to come together. Concepts from physics and chemistry, insights from history, mathematical ways of thinking, and ideas about the role of technology in exploring the universe all contribute to a grasp of the character of the cosmos. In particular, the role of gravity in forming and maintaining planets, stars, and the solar system should become clear. The scale of billions will make better sense, and the speed of light can be used to express relative distances conveniently. Current Version of the Benchmarks Statements By the end of the 12th grade, students should know that The stars differ from each other in size, temperature, and age, but they appear to be made up of the same elements found on earth and behave according to the same physical principles. 4AH1a Unlike the sun, most stars are in systems of two or more stars orbiting around one another. 4AH1b On the basis of scientific evidence, the universe is estimated to be over ten billion years old. The current theory is that its entire contents expanded explosively from a hot, dense, chaotic mass. 4AH2ab Stars condensed by gravity out of clouds of molecules of the lightest elements until nuclear fusion of the light elements into heavier ones began to occur. Fusion released great amounts of energy over millions of years. 4AH2cd Eventually, some stars exploded, producing clouds containing heavy elements from which other stars and planets orbiting them could later condense. The process of star formation and destruction continues. 4AH2ef Increasingly sophisticated technology is used to learn about the universe. Visual, radio, and X-ray telescopes collect information from across the entire spectrum of electromagnetic waves computers handle data and complicated computations to interpret them space probes send back data and materials from remote parts of the solar system and accelerators give subatomic particles energies that simulate conditions in the stars and in the early history of the universe before stars formed. 4AH3 Mathematical models and computer simulations are used in studying evidence from many sources in order to form a scientific account of the universe. 4AH4 As the earth and other planets formed, the heavier elements fell to their centers. On planets close to the sun (Mercury, Venus, Earth, and Mars), the lightest elements were mostly blown or boiled away by radiation from the newly formed sun on the outer planets (Jupiter, Saturn, Uranus, Neptune, and Pluto) the lighter elements still surround them as deep atmospheres of gas or as frozen solid layers. 4AH5 (SFAA) Our solar system coalesced out of a giant cloud of gas and debris left in the wake of exploding stars about five billion years ago. Everything in and on the earth, including living organisms, is made of this material. 4AH6 (SFAA) 1993 Version of the Benchmarks Statements By the end of the 12th grade, students should know that The stars differ from each other in size, temperature, and age, but they appear to be made up of the same elements that are found on the earth and to behave according to the same physical principles. Unlike the sun, most stars are in systems of two or more stars orbiting around one another. 4AH1 On the basis of scientific evidence, the universe is estimated to be over ten billion years old. The current theory is that its entire contents expanded explosively from a hot, dense, chaotic mass. Stars condensed by gravity out of clouds of molecules of the lightest elements until nuclear fusion of the light elements into heavier ones began to occur. Fusion released great amounts of energy over millions of years. Eventually, some stars exploded, producing clouds of heavy elements from which other stars and planets could later condense. The process of star formation and destruction continues. 4AH2 Increasingly sophisticated technology is used to learn about the universe. Visual, radio, and x-ray telescopes collect information from across the entire spectrum of electromagnetic waves computers handle an avalanche of data and increasingly complicated computations to interpret them space probes send back data and materials from the remote parts of the solar system and accelerators give subatomic particles energies that simulate conditions in the stars and in the early history of the universe before stars formed. 4AH3 Mathematical models and computer simulations are used in studying evidence from many sources in order to form a scientific account of the universe. 4AH4 In the current version of Benchmarks Online, the last sentence of this benchmark has been moved to grades 6-8, chapter 11, section B, and recoded as 11BM4 . B. The Earth An integrated picture of the earth has to develop over many years, with some concepts being visited over and over again in new contexts and greater detail. Some aspects can be learned in science, others in geography some parts can be purely descriptive, others must draw on physical principles. The benchmarks in this section complement those of the previous section that locate the earth in the cosmos and those of the following section that focus on the surface of the earth. This arrangement does not imply any particular order of teaching. Often, teaching near-at-hand phenomena before teaching the far-distant ones makes sense on the other hand, sometimes the near-to-far progression that makes sense cognitively may not correspond to what interests children. Perhaps the most important reason for students to study the earth repeatedly is that they take years to acquire the knowledge that they need to complete the picture. The full picture requires the introduction of such concepts as temperature, the water cycle, gravitation, states of matter, chemical concentration, and energy transfer. Understanding of these concepts grows slowly as children mature and encounter them in different contexts. The benchmarks here call for students to be able to explain two phenomenamdashthe seasons and the phases of the moon-that are usually not learned well. Most adults are unable to give even approximately correct explanations for them. Most students are told by teachers what causes the seasons and the phases of the moon, and they read about them without understanding. Moon phases are difficult because of students unfamiliarity with the geometry of light and quotseeing. quot To help figure out the geometry, students can act out the sun-earth-moon relationships and make physical models. In trying to understand the seasons, students have difficulties regarding geometry and solar radiation. Students need direct experience with light and surfacesmdashshadows, reflection, and warming effects at different angles. Kindergarten through Grade 2 There are many ways to acquaint children with earth-related phenomena that they will only come to understand later as being cyclic. For instance, students can start to keep daily records of temperature (hot, cold, pleasant) and precipitation (none, some, lots), and plot them by week, month, and years. It is enough for students to spot the pattern of ups and downs, without getting deeply into the nature of climate. They should become familiar with the freezing of water and melting of ice (with no change in weight), the disappearance of wetness into the air, and the appearance of water on cold surfaces. Evaporation and condensation will mean nothing different from disappearance and appearance, perhaps for several years, until students begin to understand that the evaporated water is still present in the form of invisibly small molecules. Current Version of the Benchmarks Statements By the end of the 2nd grade, students should know that The temperature and amount of rain (or snow) tend to be high, low, or medium in the same months every year. 4BP1 Water can be a liquid or a solid and can go back and forth from one form to the other. If water is turned into ice and then the ice is allowed to melt, the amount of water is the same as it was before freezing. 4BP2 Water left in an open container disappears, but water in a closed container does not disappear. 4BP3 1993 Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Some events in nature have a repeating pattern. The weather changes some from day to day, but things such as temperature and rain (or snow) tend to be high, low, or medium in the same months every year. 4BP1 In the current version of Benchmarks Online, the first sentence of this benchmark has been moved to grades 3-5, chapter 11, section C, and recoded as 11CE4 . Water can be a liquid or a solid and can go back and forth from one form to the other. If water is turned into ice and then the ice is allowed to melt, the amount of water is the same as it was before freezing. 4BP2 Water left in an open container disappears, but water in a closed container does not disappear. 4BP3 Grades 3 through 5 During this period, students can begin to learn some of the surface features of the earth and also the earths relation to the sun, moon, and other planets. Films, computer simulations, a planetarium, and telescopic observations will help, but it is essential that all students, sometimes working together in small groups, make physical models and explain what the models show. At the same time, students can begin learning about scale (counting, comparative distances, volumes, times, etc.) in interesting, readily understood activities and readings. However, scale factors larger than thousands, and even the idea of ratios, may be difficult before early adolescence. An important point to be made along the way is that one cannot determine how the solar system is put together just by looking at it. Diagrams show what the system would look like if people could see it from far away, a feat that cannot be accomplished. Telescopes and other instruments do provide information, but a model is really needed to make sense out of the information. (The realization that people are not able to see, from the outside, how the solar system is constructed will help students understand the basis for the Copernican Revolution when the topic arises later.) In making diagrams to show, say, the relative sizes of the planets and the distances of the planets from the sun, students may try to combine them using a single scale8212and quickly become frustrated. Perhaps this can lead to a discussion of the general limits of graphic methods (including photographs) for showing reality. In any case, at this stage a rough picture of the organization of the solar system is enough. Water offers another important set of experiences for students at this level. Students can conduct investigations that go beyond the observations made in the earlier grades to learn the connection between liquid and solid forms, but recognizing that water can also be a gas, while much more difficult, is still probably accessible. Perhaps the main thrust there is to try to figure out where water in an open container goes. This is neither self-evident nor easy to detect. But the water cycle is of such profound importance to life on earth that students should certainly have experiences that will in time contribute to their understanding of evaporation, condensation, and the conservation of matter. Current Version of the Benchmarks Statements By the end of the 5th grade, students should know that Things on or near the earth are pulled toward it by the earths gravity. 4BE1 The earth is approximately spherical in shape. Like the earth, the sun and planets are spheres. 4BE2a The rotation of the earth on its axis every 24 hours produces the night-and-day cycle. To people on earth, this turning of the planet makes it seem as though the sun, moon, planets, and stars are orbiting the earth once a day. 4BE2bc When liquid water disappears, it turns into a gas (vapor) in the air and can reappear as a liquid when cooled, or as a solid if cooled below the freezing point of water. Clouds and fog are made of tiny droplets or frozen crystals of water. 4BE3 Air is a material that surrounds us and takes up space and whose movement we feel as wind. 4BE4 The weather is always changing and can be described by measurable quantities such as temperature, wind direction and speed, and precipitation. Large masses of air with certain properties move across the surface of the earth. The movement and interaction of these air masses is used to forecast the weather. 4BE5 (NSES) 1993 Version of the Benchmarks Statements By the end of the 5th grade, students should know that Things on or near the earth are pulled toward it by the earths gravity. 4BE1 In the current version of Benchmarks Online, this benchmark has been deleted because the ideas in it are addressed in benchmark 4GE1 Like all planets and stars, the earth is approximately spherical in shape. The rotation of the earth on its axis every 24 hours produces the night-and-day cycle. To people on earth, this turning of the planet makes it seem as though the sun, moon, planets, and stars are orbiting the earth once a day. 4BE2 When liquid water disappears, it turns into a gas (vapor) in the air and can reappear as a liquid when cooled, or as a solid if cooled below the freezing point of water. Clouds and fog are made of tiny droplets of water. 4BE3 Air is a substance that surrounds us, takes up space, and whose movement we feel as wind. 4BE4 Grades 6 through 8 Students can now consolidate their prior knowledge of the earth (as a planet) by adding more details (especially about climate), getting a firmer grasp of the geometry involved in explaining the seasons and phases of the moon, improving their ability to handle scale, and shifting their frame of reference away from the earth when needed. An inevitable paradox of the large scales involved is that an ocean that is difficult to imagine being 7 miles deep also can be considered a relatively thin layer on the earths surface. Students should exercise their understanding of the paradox, perhaps by debating provocative questions such as Is the ocean amazingly deep or amazingly shallow Gravity, earlier thought of as acting toward the ground, can by now be thought of as acting toward the center of the spherical earth and reaching indefinitely into space. It is also time for students to begin to look at the planets role in sustaining life8212a complex subject that involves many different issues and benchmarks. In this section, the emphasis is on water and air as essential resources. The cause of the seasons is a subtle combination of global and orbital geometry and of the effects of radiation at different angles. Students can learn part of the story at this grade level, but a complete picture cannot be expected until later. Current Version of the Benchmarks Statements By the end of the 8th grade, students should know that The earth is mostly rock. Three-fourths of the earths surface is covered by a relatively thin layer of water (some of it frozen), and the entire planet is surrounded by a relatively thin layer of air. 4BM2ab Earth is the only body in the solar system that appears able to support life. The other planets have compositions and conditions very different from the earths. 4BM2cd Everything on or anywhere near the earth is pulled toward the earths center by gravitational force. 4BM3 The moons orbit around the earth once in about 28 days changes what part of the moon is lighted by the sun and how much of that part can be seen from the earth - the phases of the moon. 4BM5 Climates have sometimes changed abruptly in the past as a result of volcanic eruptions or impacts of huge rocks from space. 4BM6 Water evaporates from the surface of the earth, rises and cools, condenses into rain or snow, and falls again to the surface. The water falling on land collects in rivers and lakes, soil, and porous layers of rock, and much of it flows back into the oceans. The cycling of water in and out of the atmosphere is a significant aspect of the weather patterns on Earth. 4BM7 Fresh water, limited in supply, is essential for some organisms and industrial processes. Water in rivers, lakes, and underground can be depleted or polluted, making it unavailable or unsuitable for life. 4BM8 Thermal energy carried by ocean currents has a strong influence on climates around the world. Areas near oceans tend to have more moderate temperatures than they would if they were farther inland but at the same latitude because water in the oceans can hold a large amount of thermal energy. 4BM9 Some material resources are very rare and some exist in great quantities. The ability to obtain and process resources depends on where they are located and the form they are in. As resources are depleted, they may become more difficult to obtain. 4BM10ab Recycling materials and the development of substitutes for those materials can reduce the rate of depletion of resources but may also be costly. Some materials are not easily recycled. 4BM10c The wasteful or unnecessary use of natural resources can limit their availability for other purposes. Restoring depleted soil, forests, or fishing grounds can be difficult and costly. 4BM11a The benefits of Earths resourcessuch as fresh water, air, soil, and treescan be reduced by deliberately or inadvertently polluting them. The atmosphere, the oceans, and the land have a limited capacity to absorb and recycle waste materials. In addition, some materials take a long time to degrade. Therefore, cleaning up polluted air, water, or soil can be difficult and costly. 4BM11bc The temperature of a place on the earths surface tends to rise and fall in a somewhat predictable pattern every day and over the course of a year. The pattern of temperature changes observed in a place tends to vary depending on how far north or south of the equator the place is, how near to oceans it is, and how high above sea level it is. 4BM12 The number of hours of daylight and the intensity of the sunlight both vary in a predictable pattern that depends on how far north or south of the equator the place is. This variation explains why temperatures vary over the course of the year and at different locations. 4BM13 The earth has a variety of climates, defined by average temperature, precipitation, humidity, air pressure, and wind, over time in a particular place. 4BM14 The atmosphere is a mixture of nitrogen, oxygen, and trace amounts of water vapor, carbon dioxide, and other gases. 4BM15 (NSES) 1993 Version of the Benchmarks Statements By the end of the 8th grade, students should know that We live on a relatively small planet, the third from the sun in the only system of planets definitely known to exist (although other, similar systems may be discovered in the universe). 4BM1 In the current version of Benchmarks Online, this benchmark has been deleted. The earth is mostly rock. Three-fourths of its surface is covered by a relatively thin layer of water (some of it frozen), and the entire planet is surrounded by a relatively thin blanket of air. It is the only body in the solar system that appears able to support life. The other planets have compositions and conditions very different from the earths. 4BM2 Everything on or anywhere near the earth is pulled toward the earths center by gravitational force. 4BM3 Because the earth turns daily on an axis that is tilted relative to the plane of the earths yearly orbit around the sun, sunlight falls more intensely on different parts of the earth during the year. The difference in heating of the earths surface produces the planets seasons and weather patterns. 4BM4 In the current version of Benchmarks Online, this benchmark has been moved to grades 912 and recoded as 4BH3 . The moons orbit around the earth once in about 28 days changes what part of the moon is lighted by the sun and how much of that part can be seen from the earththe phases of the moon. 4BM5 Climates have sometimes changed abruptly in the past as a result of changes in the earths crust, such as volcanic eruptions or impacts of huge rocks from space. Even relatively small changes in atmospheric or ocean content can have widespread effects on climate if the change lasts long enough. 4BM6 The cycling of water in and out of the atmosphere plays an important role in determining climatic patterns. Water evaporates from the surface of the earth, rises and cools, condenses into rain or snow, and falls again to the surface. The water falling on land collects in rivers and lakes, soil, and porous layers of rock, and much of it flows back into the ocean. 4BM7 Fresh water, limited in supply, is essential for life and also for most industrial processes. Rivers, lakes, and groundwater can be depleted or polluted, becoming unavailable or unsuitable for life. 4BM8 Heat energy carried by ocean currents has a strong influence on climate around the world. 4BM9 Some minerals are very rare and some exist in great quantities, butfor practical purposesthe ability to recover them is just as important as their abundance. As minerals are depleted, obtaining them becomes more difficult. Recycling and the development of substitutes can reduce the rate of depletion but may also be costly. 4BM10 The benefits of the earths resourcessuch as fresh water, air, soil, and treescan be reduced by using them wastefully or by deliberately or inadvertently destroying them. The atmosphere and the oceans have a limited capacity to absorb wastes and recycle materials naturally. Cleaning up polluted air, water, or soil or restoring depleted soil, forests, or fishing grounds can be very difficult and costly. 4BM11 Grades 9 through 12 Two important strands of understanding can now be pulled together to enrich students views of the physical setting. One strand connects such physical concepts and principles as energy, gravitation, conservation, and radiation to the descriptive picture that students have built in their minds about the operation of the planets. The other strand consists of the Copernican Revolution, which illustrates the place of technology, mathematics, experimentation, and theory in scientific breakthroughs. In the context of thinking about how the solar system is put together, this historical event unites physics and astronomy, involves colorful personalities, and raises deep philosophical and political issues. Current Version of the Benchmarks Statements By the end of the 12th grade, students should know that Life is adapted to conditions on the earth, including the force of gravity that enables the planet to retain an adequate atmosphere, and an intensity of electromagnetic waves from the sun that allows water to be present in the liquid state. 4BH1 Transfer of thermal energy between the atmosphere and the land or oceans produces temperature gradients in the atmosphere and the oceans. Regions at different temperatures rise or sink or mix, resulting in winds and ocean currents. These winds and ocean currents, which are also affected by the earths rotation and the shape of the land, carry thermal energy from warm to cool areas. 4BH2 Because the earth turns daily on an axis that is tilted relative to the plane of the earths yearly orbit around the sun, sunlight falls more intensely on different parts of the earth during the year. The difference in intensity of sunlight and the resulting warming of the earths surface produces the seasonal variations in temperature. 4BH3 (BSL) Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, are transparent to much of the incoming sunlight but not to the infrared light from the warmed surface of the earth. When greenhouse gases increase, more thermal energy is trapped in the atmosphere, and the temperature of the earth increases the light energy radiated into space until it again equals the light energy absorbed from the sun. 4BH4 (SFAA) Climatic conditions result from latitude, altitude, and from the position of mountain ranges, oceans, and lakes. Dynamic processes such as cloud formation, ocean currents, and atmospheric circulation patterns influence climates as well. 4BH5 (NSES) The earths climates have changed in the past, are currently changing, and are expected to change in the future, primarily due to changes in the amount of light reaching places on the earth and the composition of the atmosphere. The burning of fossil fuels in the last century has increased the amount of greenhouse gases in the atmosphere, which has contributed to Earths warming. 4BH6 (SFAA) The earth has many natural resources of great importance to human life. Some are readily renewable, some are renewable only at great cost, and some are not renewable at all. 4BH8 (SFAA) Although the earth has a great capacity to absorb and recycle materials naturally, ecosystems have only a finite capacity to withstand change without experiencing major ecological alterations that may also have adverse effects on human activities. 4BH9 (SFAA) 1993 Version of the Benchmarks Statements By the end of the 12th grade, students should know that Life is adapted to conditions on the earth, including the force of gravity that enables the planet to retain an adequate atmosphere, and an intensity of radiation from the sun that allows water to cycle between liquid and vapor. 4BH1 Weather (in the short run) and climate (in the long run) involve the transfer of energy in and out of the atmosphere. Solar radiation heats the land masses, oceans, and air. Transfer of heat energy at the boundaries between the atmosphere, the land masses, and the oceans results in layers of different temperatures and densities in both the ocean and atmosphere. The action of gravitational force on regions of different densities causes them to rise or falland such circulation, influenced by the rotation of the earth, produces winds and ocean currents. 4BH2 C. Processes that Shape the Earth Students should learn what causes earthquakes, volcanos, and floods and how those events shape the surface of the earth. Students, however, may show more interest in the phenomena than in the role the phenomena play in sculpting the earth. So teachers should start with students immediate interests and work toward the science. Students may find it harder to take seriously the less-obvious, less-dramatic, long-term effects of erosion by wind and water, annual deposits of sediment, the creep of continents, and the rise of mountains. Students recognition of those effects will depend on an improving sense of long time periods and familiarity with the effect of multiplying tiny fractions by very large numbers (in this case, slow rates by long times). Students can start in the early grades with the ways in which organisms, themselves included, modify their surroundings. As people have used earth resources, they have altered some earth systems. Students can gradually come to recognize how human behavior affects the earths capacity to sustain life. Questions of environmental policy should be pursued when students become interested in them, usually in the middle grades or later, but care should be taken not to bypass science for advocacy. Critical thinking based on scientific concepts and understanding is the primary goal for science education. Kindergarten through Grade 2 Teaching geological facts about how the face of the earth changes serves little purpose in these early years. Students should start becoming familiar with all aspects of their immediate surroundings, including what things change and what seems to cause change. Perhaps changing things can be a category in a class portfolio of things students observe and read about. At some point, students can start thinking up and trying out safe and helpful ways to change parts of their environment. Current Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Chunks of rocks come in many sizes and shapes, from boulders to grains of sand and even smaller. 4CP1 Change is something that happens to many things. 4CP2 Animals and plants sometimes cause changes in their surroundings. 4CP3 1993 Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Chunks of rocks come in many sizes and shapes, from boulders to grains of sand and even smaller. 4CP1 Change is something that happens to many things. 4CP2 Animals and plants sometimes cause changes in their surroundings. 4CP3 Grades 3 through 5 In these years, students should accumulate more information about the physical environment, becoming familiar with the details of geological features, observing and mapping locations of hills, valleys, rivers, etc. but without elaborate classification. Students should also become adept at using magnifiers to inspect a variety of rocks and soils. The point is not to classify rigorously but to notice the variety of components. Students should now observe elementary processes of the rock cyclemdasherosion, transport, and deposit. Water and sand boxes and rock tumblers can provide them with some firsthand examples. Later, they can connect the features to the processes and follow explanations of how the features came to be and still are changing. Students can build devices for demonstrating how wind and water shape the land and how forces on materials can make wrinkles, folds, and faults. Films of volcanic magma and ash ejection dramatize another source of buildup. Current Version of the Benchmarks Statements By the end of the 5th grade, students should know that Waves, wind, water, and ice shape and reshape the earths land surface by eroding rock and soil in some areas and depositing them in other areas, sometimes in seasonal layers. 4CE1 Rock is composed of different combinations of minerals. Smaller rocks come from the breakage and weathering of bedrock and larger rocks. Soil is made partly from weathered rock, partly from plant remainsand also contains many living organisms. 4CE2 1993 Version of the Benchmarks Statements By the end of the 5th grade, students should know that Waves, wind, water, and ice shape and reshape the earths land surface by eroding rock and soil in some areas and depositing them in other areas, sometimes in seasonal layers. 4CE1 Rock is composed of different combinations of minerals. Smaller rocks come from the breakage and weathering of bedrock and larger rocks. Soil is made partly from weathered rock, partly from plant remainsand also contains many living organisms. 4CE2 Grades 6 through 8 At this level, students are able to complete most of their understanding of the main features of the physical and biological factors that shape the face of the earth. This understanding will still be descriptive because the theory of plate tectonics will not be encountered formally until high school. Of course, students should see as great a variety of landforms and soils as possible. It is especially important that students come to understand how sedimentary rock is formed periodically, embedding plant and animal remains and leaving a record of the sequence in which the plants and animals appeared and disappeared. Besides the relative age of the rock layers, the absolute age of those remains is central to the argument that there has been enough time for evolution of species. The process of sedimentation is understandable and observable. But imagining the span of geologic time will be difficult for students. Current Version of the Benchmarks Statements By the end of the 8th grade, students should know that The interior of the earth is hot. Heat flow and movement of material within the earth cause earthquakes and volcanic eruptions and create mountains and ocean basins. Gas and dust from large volcanoes can change the atmosphere. 4CM1 Some changes in the earths surface are abrupt (such as earthquakes and volcanic eruptions) while other changes happen very slowly (such as uplift and wearing down of mountains). 4CM2a The earths surface is shaped in part by the motion of water (including ice) and wind over very long times, which acts to level mountain ranges. Rivers and glacial ice carry off soil and break down rock, eventually depositing the material in sediments or carrying it in solution to the sea. 4CM2b Sediments of sand and smaller particles (sometimes containing the remains of organisms) are gradually buried and are cemented together by dissolved minerals to form solid rock again. 4CM3 Sedimentary rock buried deep enough may be re-formed by pressure and heat, perhaps melting and recrystallizing into different kinds of rock. These re-formed rock layers may be forced up again to become land surface and even mountains. Subsequently, this new rock too will erode. Rock bears evidence of the minerals, temperatures, and forces that created it. 4CM4 Thousands of layers of sedimentary rock confirm the long history of the changing surface of the earth and the changing life forms whose remains are found in successive layers. The youngest layers are not always found on top, because of folding, breaking, and uplift of layers. 4CM5 Although weathered rock is the basic component of soil, the composition and texture of soil and its fertility and resistance to erosion are greatly influenced by plant roots and debris, bacteria, fungi, worms, insects, rodents, and other organisms. 4CM6 Human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals released into the atmosphere, and intensive farming, have changed the earths land, oceans, and atmosphere. Some of these changes have decreased the capacity of the environment to support some life forms. 4CM7 There are a variety of different land forms on the earths surface (such as coastlines, rivers, mountains, deltas, and canyons). 4CM8 (BSL) Matching coastlines and similarities in rock types and life forms suggest that todays continents are separated parts of what was long ago a single continent. 4CM9 (SFAA) The earth first formed in a molten state and then the surface cooled into solid rock. 4CM10 (ASL) The outer layer of the earthincluding both the continents and the ocean basinsconsists of separate plates. 4CM11 (BSL) The earths plates sit on a dense, hot, somewhat melted layer of the earth. The plates move very slowly, pressing against one another in some places and pulling apart in other places, sometimes scraping alongside each other as they do. Mountains form as two continental plates, or an ocean plate and a continental plate, press together. 4CM12 (BSL) There are worldwide patterns to major geological events (such as earthquakes, volcanic eruptions, and mountain building) that coincide with plate boundaries. 4CM13 (BSL) 1993 Version of the Benchmarks Statements By the end of the 8th grade, students should know that The interior of the earth is hot. Heat flow and movement of material within the earth cause earthquakes and volcanic eruptions and create mountains and ocean basins. Gas and dust from large volcanoes can change the atmosphere. 4CM1 Some changes in the earths surface are abrupt (such as earthquakes and volcanic eruptions) while other changes happen very slowly (such as uplift and wearing down of mountains). The earths surface is shaped in part by the motion of water and wind over very long times, which act to level mountain ranges. 4CM2 Sediments of sand and smaller particles (sometimes containing the remains of organisms) are gradually buried and are cemented together by dissolved minerals to form solid rock again. 4CM3 Sedimentary rock buried deep enough may be reformed by pressure and heat, perhaps melting and recrystallizing into different kinds of rock. These re-formed rock layers may be forced up again to become land surface and even mountains. Subsequently, this new rock too will erode. Rock bears evidence of the minerals, temperatures, and forces that created it. 4CM4 Thousands of layers of sedimentary rock confirm the long history of the changing surface of the earth and the changing life forms whose remains are found in successive layers. The youngest layers are not always found on top, because of folding, breaking, and uplift of layers. 4CM5 Although weathered rock is the basic component of soil, the composition and texture of soil and its fertility and resistance to erosion are greatly influenced by plant roots and debris, bacteria, fungi, worms, insects, rodents, and other organisms. 4CM6 Human activities, such as reducing the amount of forest cover, increasing the amount and variety of chemicals released into the atmosphere, and intensive farming, have changed the earths land, oceans, and atmosphere. Some of these changes have decreased the capacity of the environment to support some life forms. 4CM7 Grades 9 through 12 Grades 3 through 5 Investing much time and effort in developing formal energy concepts can wait. The importance of energy, after all, is that it is a useful idea. It helps make sense out of a very large number of things that go on in the physical and biological and engineering worlds. But until students have reached a certain point in their understanding of bits and pieces of the world, they gain little by having such a tool. It is a matter of timing. The one aspect of the energy story in which students of this age can make some headway is heat, which is produced almost everywhere. In their science and technology activities during these years, students should be alerted to look for things and processes that give off heatmdashlights, radios, television sets, the sun, sawing wood, polishing surfaces, bending things, running motors, people, animals, etc. mdashand then for those that seem not to give off heat. Also, the time is appropriate to explore how heat spreads from one place to another and what can be done to contain it or shield things from it. Students ideas of heat have many wrinkles. In some situations, cold is thought to be transferred rather than heat. Some materials may be thought to be intrinsically warm (blankets) or cold (metals). Objects that keep things warmmdashsuch as a sweater or mittensmdashmay be thought to be sources of heat. Only a continuing mix of experiment and discussion is likely to dispel these ideas. Students need not come out of this grade span understanding heat or its difference from temperature. In this spirit, there is little to be gained by having youngsters refer to heat as heat energy . More important, students should become familiar with the warming of objects that start out cooler than their environment, and vice versa. Computer labware probes and graphic displays that detect small changes in temperature and plot them can be used by students to examine many instances of heat exchange. Because many students think of cold as a substance that spreads like heat, there may be some advantage in translating descriptions of transfer of cold into terms of transfer of heat. Current Version of the Benchmarks Statements By the end of the 5th grade, students should know that When two objects are rubbed against each other, they both get warmer. In addition, many mechanical and electrical devices get warmer when they are used. 4EE1 When warmer things are put with cooler ones, the warmer things get cooler and the cooler things get warmer until they all are the same temperature. 4EE2a When warmer things are put with cooler ones, heat is transferred from the warmer ones to the cooler ones. 4EE2b A warmer object can warm a cooler one by contact or at a distance. 4EE2c 1993 Version of the Benchmarks Statements By the end of the 5th grade, students should know that Things that give off light often also give off heat. Heat is produced by mechanical and electrical machines, and any time one thing rubs against something else. 4EE1 When warmer things are put with cooler ones, the warm ones lose heat and the cool ones gain it until they are all at the same temperature. A warmer object can warm a cooler one by contact or at a distance. 4EE2 Some materials conduct heat much better than others. Poor conductors can reduce heat loss. 4EE3 In the current version of Benchmarks Online, this benchmark has been deleted because the ideas in it are addressed in benchmark 4DE6 Grades 6 through 8 At this level, students should be introduced to energy primarily through energy transformations. Students should trace where energy comes from (and goes next) in examples that involve several different forms of energy along the way: heat, light, motion of objects, chemical, and elastically distorted materials. To change somethings speed, to bend or stretch things, to heat or cool them, to push things together or tear them apart all require transfers (and some transformations) of energy. At this early stage, there may be some confusion in students minds between energy and energy sources . Focusing on energy transformations may get around this somewhat. Food, gasoline, and batteries obviously get used up. But the energy they contain does not disappear it is changed into other forms of energy. The most primitive idea is that the energy needed for an event must come from somewhere. That should trigger childrens interest in asking, for any situation, where the energy comes from and (later) asking where it goes. Where it comes from is usually much more evident than where it goes, because some usually diffuses away as radiation and random molecular motion. A slightly more sophisticated proposition is the semiquantitative one that whenever some energy seems to show up in one place, some will be found to disappear from another. Eventually, the energy idea can become quantitative: If we can keep track of how much energy of each kind increases and decreases, we find that whenever the energy in one place decreases, the energy in other places increases by just the same amount . This energy-cannot-be-created-or-destroyed way of stating conservation fully may be more intuitive than the abstraction of a constant energy total within an isolated system. The quantitative (equal amounts) idea should probably wait until high school. Convection is not so much an independent means of heat transfer as it is an aid to transfer of heat by conduction and radiation. Convection currents appear spontaneously when density differences caused by heating (conduction and radiation) are acted on by a gravitational field. (Though not in space stations, unless they are rotating.) But these subtleties are not appropriate for most 8th graders. Current Version of the Benchmarks Statements By the end of the 8th grade, students should know that Whenever energy appears in one place, it must have disappeared from another. Whenever energy is lost from somewhere, it must have gone somewhere else. Sometimes when energy appears to be lost, it actually has been transferred to a system that is so large that the effect of the transferred energy is imperceptible. 4EM1 Energy can be transferred from one system to another (or from a system to its environment) in different ways: 1) thermally, when a warmer object is in contact with a cooler one 2) mechanically, when two objects push or pull on each other over a distance 3) electrically, when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device or 4) by electromagnetic waves. 4EM2 Thermal energy is transferred through a material by the collisions of atoms within the material. Over time, the thermal energy tends to spread out through a material and from one material to another if they are in contact. Thermal energy can also be transferred by means of currents in air, water, or other fluids. In addition, some thermal energy in all materials is transformed into light energy and radiated into the environment by electromagnetic waves that light energy can be transformed back into thermal energy when the electromagnetic waves strike another material. As a result, a material tends to cool down unless some other form of energy is converted to thermal energy in the material. 4EM3 Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves. 4EM4 Light and other electromagnetic waves can warm objects. How much an objects temperature increases depends on how intense the light striking its surface is, how long the light shines on the object, and how much of the light is absorbed. 4EM6 1993 Version of the Benchmarks Statements By the end of the 8th grade, students should know that Energy cannot be created or destroyed, but only changed from one form into another. 4EM1 Most of what goes on in the universefrom exploding stars and biological growth to the operation of machines and the motion of peopleinvolves some form of energy being transformed into another. Energy in the form of heat is almost always one of the products of an energy transformation. 4EM2 Heat can be transferred through materials by the collisions of atoms or across space by radiation. If the material is fluid, currents will be set up in it that aid the transfer of heat. 4EM3 Energy appears in different forms. Heat energy is in the disorderly motion of molecules chemical energy is in the arrangement of atoms mechanical energy is in moving bodies or in elastically distorted shapes gravitational energy is in the separation of mutually attracting masses. 4EM4 Grades 9 through 12 The concepts acquired in the earlier grades should now be extended to nuclear realms and living organisms. Revisiting energy concepts in new contexts provides opportunities to improve student understanding of the basic concepts and to see just how powerful they are. Two other major ideas merit introduction during these years, but without resort to mathematics. One of these is that the total amount of energy available for useful transformation is almost always decreasing the other is that energy changes on the atomic scale occur only in discrete jumps. The first of those is not too difficult or implausible for students because they can experience in many ways a wide variety of actions that give off heat. The emphasis should probably be on the practical consequences of the loss of useful energy through heat dissipation. On the other hand, the notion that energy changes in atoms can occur in only fixed amounts with no intermediate values is strange to begin with and hard to demonstrate. Some evidence should be presented for this scientific belief but not in great detail. The easiest phenomenon to show, which is also a major reason for including quantum jumps in literacy, is the discrete colors of light emitted by separate atoms, as in sodium-vapor or mercury-vapor lights. Another major reason for having students encounter the quantum idea is to illustrate the point that in science it is sometimes useful to invent ideas that run counter to intuition and prior experience. An important application of the atomenergy relationship to bring to the attention of students is that the distinctive light energies emitted or absorbed by different atoms enable them to be identified on earth, in our sun, and even on the other side of the universe. This fact is a prime example of the rules are the same everywhere principle. Current Version of the Benchmarks Statements By the end of the 12th grade, students should know that Although the various forms of energy appear very different, each can be measured in a way that makes it possible to keep track of how much of one form is converted into another. Whenever the amount of energy in one place diminishes, the amount in other places or forms increases by the same amount. 4EH1 In any system of atoms or molecules, the statistical odds are that the atoms or molecules will end up with less order than they originally had and that the thermal energy will be spread out more evenly. The amount of order in a system may stay the same or increase, but only if the surrounding environment becomes even less ordered. The total amount of order in the universe always tends to decrease. 4EH2 As energy spreads out, whether by conduction, convection, or radiation, the total amount of energy stays the same. However, since it is spread out, less can be done with it. 4EH3 Chemical energy is associated with the configuration of atoms in molecules that make up a substance. Some changes of configuration require a net input of energy whereas others cause a net release. 4EH4 When energy of an isolated atom or molecule changes, it does so in a definite jump from one value to another, with no possible values in between. The change in energy occurs when light is absorbed or emitted, so the light also has distinct energy values. The light emitted or absorbed by separate atoms or molecules (as in a gas) can be used to identify what the substance is. 4EH5 Energy is released whenever the nuclei of very heavy atoms, such as uranium or plutonium, split into middleweight ones, or when very light nuclei, such as those of hydrogen and helium, combine into heavier ones. For a given quantity of a substance, the energy released in a nuclear reaction is very much greater than the energy given off in a chemical reaction. 4EH6 Thermal energy in a system is associated with the disordered motions of its atoms or molecules. Gravitational energy is associated with the separation of mutually attracting masses. Electrical potential energy is associated with the separation of mutually attracting or repelling charges. 4EH7 (BSL) In a fluid, regions that have different temperatures have different densities. The action of a gravitational force on regions of different densities causes them to rise or fall, creating currents that contribute to the transfer of energy. 4EH8 (BSL) Many forms of energy can be considered to be either kinetic energy, which is the energy of motion, or potential energy, which depends on the separation between mutually attracting or repelling objects. 4EH9 (NSES) If no energy is transferred into or out of a system, the total energy of all the different forms in the system will not change, no matter what gradual or violent changes actually occur within the system. 4EH10 (SFAA) 1993 Version of the Benchmarks Statements By the end of the 12th grade, students should know that Whenever the amount of energy in one place or form diminishes, the amount in other places or forms increases by the same amount. 4EH1 Heat energy in a material consists of the disordered motions of its atoms or molecules. In any interactions of atoms or molecules, the statistical odds are that they will end up with less order than they beganthat is, with the heat energy spread out more evenly. With huge numbers of atoms and molecules, the greater disorder is almost certain. 4EH2 Transformations of energy usually produce some energy in the form of heat, which spreads around by radiation or conduction into cooler places. Although just as much total energy remains, its being spread out more evenly means less can be done with it. 4EH3 Different energy levels are associated with different configurations of atoms and molecules. Some changes of configuration require an input of energy whereas others release energy. 4EH4 When energy of an isolated atom or molecule changes, it does so in a definite jump from one value to another, with no possible values in between. The change in energy occurs when radiation is absorbed or emitted, so the radiation also has distinct energy values. As a result, the light emitted or absorbed by separate atoms or molecules (as in a gas) can be used to identify what the substance is. 4EH5 Energy is released whenever the nuclei of very heavy atoms, such as uranium or plutonium, split into middleweight ones, or when very light nuclei, such as those of hydrogen and helium, combine into heavier ones. The energy released in each nuclear reaction is very much greater than the energy given off in each chemical reaction. 4EH6 Nothing in the universe is at rest. Motion is as essential to understanding the physical world as matter and energy are. Following the organization of Science for All Americans . the benchmarks for motion constitute a wide range of topics, from the movement of objects to vibrations and the behavior of waves. Rotary motion, as interesting as it is, poses much greater difficulties for students and is not included in the benchmarks. The benchmarks for understanding the motion of objects and repeating patterns of motion do not demand the use of equations. For purposes of science literacy, a qualitative understanding is sufficient. Equations may clarify relationships for the most mathematically apt students, but for many students they are difficult and may obscure the ideas rather than clarify them. For example, almost all students can grasp that the effect of a force on an objects motion will be greater if the force is greater and will be less if the object has more massmdashbut learning aFm (which to many teachers seems like the same thing) is apparently much harder. Newtons laws of motion are simple to state, and sometimes teachers mistake the ability of students to recite the three laws correctly as evidence that they understand them. The fact that it took such a long time, historically, to codify the laws of motion suggests that they are not self-evident truths, no matter how obvious they may seem to us once we understand them well. Much research in recent years has documented that students typically have trouble relating formal ideas of motion and force to their personal view of how the world works. These are three of the obstacles: A basic problem is the ancient perception that sustained motion requires sustained force. The contrary notion that it takes force to change an objects motion, that something in motion will move in a straight line forever without slowing down unless a force acts on it, runs counter to what we can see happening with our eyes. Limitations in describing motion may keep students from learning about the effect of forces. Students of all ages tend to think in terms of motion or no motion. So the first task may be to help students divide the category of motion into steady motion, speeding up, and slowing down. For example, falling objects should be described as falling faster and faster rather than just falling down. As indicated earlier, the basic idea expressed in Newtons second law of motion is not difficult to grasp, but vocabulary may get in the way if students have to struggle over the meaning of force and acceleration. Both terms have many meanings in common language that confound their specialized use in science. Like inertia, the action-equals-reaction principle is counterintuitive. To say that a book presses down on the table is sensible enough, but then to say that the table pushes back up with exactly the same force (which disappears the instant you pick up the book) seems false on the face of it. What is to be done Students should have lots of experiences to shape their intuition about motion and forces long before encountering laws. Especially helpful are experimentation and discussion of what happens as surfaces become more elastic or more free of friction. Vibrations treated only descriptively bring no special problems, other than the occasional confusion caused by the word speed being used in English for both frequency and velocity. Does a guitar string move quickly (back and forth a thousand times a second) or slowly (only 15 miles or so per hour) Similarly, is the earths rotation slow (once a day) or fast (1,000 miles per hour at the equator) In the overall story of motion, vibrations serve in good part to introduce the ideas of frequency and amplitude. Because there are so many examples of vibrating systems that students can experience directly, they easily see vibration as a common way for some things to move and see frequency as a measure of that motion. Waves, on the other hand, present a greater challenge. Wave motion is familiar to children through their experience with water. Surface waves on water provide the standard image of what waves are, and ropes and springs can also be used to show some of the properties of waves. Without formal schooling, young people learn that many other kinds of waves exist: radio waves, x rays, radar, microwaves, sound waves, ultraviolet radiation, and more. But they still might not know what these things are, how they relate to one another, what they have to do with motion, or in what sense such waves are waves. Kindergarten through Grade 2 From the outset, students should view, describe, and discuss all kinds of moving things8212themselves, insects, birds, trees, doors, rain, fans, swings, volleyballs, wagons, stars, etc.8212keeping notes, drawing pictures to suggest their motion, and raising questions: Do they move in a straight line Is their motion fast or slow How can you tell How many ways does a growing plant move The questions count more than the answers, at this stage. And students should gain varied experiences in getting things to move or not to move and in changing the direction or speed of things that are already in motion. Presumably students will start making music from the first day in school, and this provides an opportunity to introduce vibrations as a phenomenon rather than a theory. With the drums, bells, stringed and other instruments they use, including their own voices, they can feel the vibrations on the instruments as they hear the sounds. These experiences are important for their own sake and at this point do not need elaboration. Current Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Things move in many different ways, such as straight, zigzag, round and round, back and forth, and fast and slow. 4FP1 The way to change how something is moving is to give it a push or a pull. 4FP2 Things that make sound vibrate. 4FP3 1993 Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Things move in many different ways, such as straight, zigzag, round and round, back and forth, and fast and slow. 4FP1 The way to change how something is moving is to give it a push or a pull. 4FP2 Things that make sound vibrate. 4FP3 Grades 3 through 5 Students should continue describing motion. And they can be more experimental and more quantitative as their measurement skills sharpen. Determining the speed of fast things and slow things can present a challenge that students will readily respond to. They also can work out for themselves some of the general relationships between force and change of motion and internalize the notion of force as a push or pull of one thing on another8212whether rubber bands, magnets, or explosions. Students should also increase their inventory of examples of periodic motion and perhaps devise ways of measuring different rates of vibration. And students should use prisms to see that white light produces a whole rainbow of colors. (The idea that white light is made up of different colors is difficult and should be postponed to later grades.) There is nothing to be gained at this stage, however, from linking light to wave motion. Current Version of the Benchmarks Statements By the end of the 5th grade, students should know that Changes in speed or direction of motion are caused by forces. 4FE1a The greater the force is, the greater the change in motion will be. The more massive an object is, the less effect a given force will have. 4FE1bc How fast things move differs greatly. Some things are so slow that their journey takes a long time others move too fast for people to even see them. 4FE2 Light travels and tends to maintain its direction of motion until it interacts with an object or material. Light can be absorbed, redirected, bounced back, or allowed to pass through. 4FE3 (ASL) 1993 Version of the Benchmarks Statements By the end of the 5th grade, students should know that Changes in speed or direction of motion are caused by forces. The greater the force is, the greater the change in motion will be. The more massive an object is, the less effect a given force will have. 4FE1 How fast things move differs greatly. Some things are so slow that their journey takes a long time others move too fast for people to even see them. 4FE2 Grades 6 through 8 The forcemotion relationship can be developed more fully now and the difficult idea of inertia be given attention. Students have no trouble believing that an object at rest stays that way unless acted on by a force they see it every day. The difficult notion is that an object in motion will continue to move unabated unless acted on by a force. Telling students to disregard their eyes will not do the trickmdashthe things around them do appear to slow down of their own accord unless constantly pushed or pulled. The more experiences the students can have in seeing the effect of reducing friction, the easier it may be to get them to imagine the friction-equals-zero case. Students can now learn some of the properties of waves by using water tables, ropes, and springs, and quite separately they can learn about the electromagnetic spectrum, including the assertion that it consists of wavelike radiations. Wave length should be the property receiving the most attention but only minimal calculation. Current Version of the Benchmarks Statements By the end of the 8th grade, students should know that Light from the sun is made up of a mixture of many different colors of light, even though to the eye the light looks almost white. Other things that give off or reflect light have a different mix of colors. 4FM1 Something can be seen when light waves emitted or reflected by it enter the eyejust as something can be heard when sound waves from it enter the ear. 4FM2 An unbalanced force acting on an object changes its speed or direction of motion, or both. 4FM3a If a force acts towards a single center, the objects path may curve into an orbit around the center. 4FM3b Vibrations in materials set up wavelike disturbances that spread away from the source. Sound and earthquake waves are examples. These and other waves move at different speeds in different materials. 4FM4 Human eyes respond to only a narrow range of wavelengths of electromagnetic waves-visible light. Differences of wavelength within that range are perceived as differences of color. 4FM5 Light acts like a wave in many ways. And waves can explain how light behaves. 4FM6 (ASL) Wave behavior can be described in terms of how fast the disturbance spreads, and in terms of the distance between successive peaks of the disturbance (the wavelength). 4FM7 (SFAA) There are a great variety of electromagnetic waves: radio waves, microwaves, infrared waves, visible light, ultraviolet rays, X-rays, and gamma rays. These wavelengths vary from radio waves, the longest, to gamma rays, the shortest. 4FM8 (BSL) 1993 Version of the Benchmarks Statements By the end of the 8th grade, students should know that Light from the sun is made up of a mixture of many different colors of light, even though to the eye the light looks almost white. Other things that give off or reflect light have a different mix of colors. 4FM1 Something can be seen when light waves emitted or reflected by it enter the eyejust as something can be heard when sound waves from it enter the ear. 4FM2 An unbalanced force acting on an object changes its speed or path of motion, or both. If the force acts toward a single center, the objects path may curve into an orbit around the center. 4FM3 Vibrations in materials set up wavelike disturbances that spread away from the source. Sound and earthquake waves are examples. These and other waves move at different speeds in different materials. 4FM4 Human eyes respond to only a narrow range of wavelengths of electromagnetic radiationvisible light. Differences of wavelength within that range are perceived as differences in color. 4FM5 Grades 9 through 12 At this level, students learn about relative motion, the actionreaction principle, wave behavior, the interaction of waves with matter, the Doppler effect now used in weather observations, and the red shift of distant galaxies. Relative motion is fun8212students find it interesting to figure out their speeds in different reference frames, and many activities and films illustrate this principle. Learning this concept is important for its own sake and for the part it plays in the changing reference frames of the Copernican Revolution, and in simple relativity. This level is also a time to show the power of mathematics. Once students are fully convinced that change in motion is proportional to the force applied, then mathematical logic requires that when F 0, there be no change in motion. (So Newtons first law is just a special case of his second.) Students can move from a qualitative understanding of the forcemotion relationship (more force changes motion more more mass is harder to change) to one that is more quantitative (the change in motion is directly proportional to the amount of force and inversely proportional to the mass). Experimentally, they can learn that the change in motion of an object is proportional to the applied force and inversely proportional to the mass8212a step beyond knowing that change in motion goes up with increasing force and down with increasing mass. Students should come to understand qualitatively that (1) doubling the force on an object of a given mass doubles the effect the force has, tripling triples the effect, and so on and (2) that whatever effect a given force has on an object, it will have half the effect on an object having twice the mass, a third on one having triple the mass, and so on. This need not entail having students solving lots of numerical problems. The qualitative principle also applies to waves. Even as simple a relationship as speed wavelength x frequency poses difficulties for many students. A sufficient minimum is that students develop semiquantitative notions about waves8212for example, higher frequencies have shorter wavelengths and those with longer wavelengths tend to spread out more around obstacles. The effect of wavelength on how waves interact with matter can be developed through intrinsically interesting phenomena8212such as the blueness of the sky and redness of sunsets resulting from light of short wavelengths being scattered most by the atmosphere, or the color of grass resulting from its absorbing light of both shorter and longer wavelengths while reflecting the intermediate green. Electromagnetic waves with different wavelengths have different effects on the human body. Some pass through the body with little effect, some tan or injure the skin, and some are absorbed in different amounts by internal organs (sometimes injuring cells). Current Version of the Benchmarks Statements By the end of the 12th grade, students should know that The change in motion (direction or speed) of an object is proportional to the applied force and inversely proportional to the mass. 4FH1 All motion is relative to whatever frame of reference is chosen, for there is no motionless frame from which to judge all motion. 4FH2 When electrically charged objects undergo a change in motion, they produce electromagnetic waves around them. 4FH3a In empty space, all electromagnetic waves move at the same speedthe speed of light. 4FH3c Whenever one thing exerts a force on another, an equal amount of force is exerted back on it. 4FH4 The observed wavelength of a wave depends upon the relative motion of the source and the observer. If either is moving toward the other, the observed wavelength is shorter if either is moving away, the wavelength is longer. 4FH5ab Because the light seen from almost all distant galaxies has longer wavelengths than comparable light here on Earth, astronomers believe that the whole universe is expanding. 4FH5c Waves can superpose on one another, bend around corners, reflect off surfaces, be absorbed by materials they enter, and change direction when entering a new material. All these effects vary with wavelength. 4FH6ab The energy of waves (like any form of energy) can be changed into other forms of energy. 4FH6c In most familiar situations, frictional forces complicate the description of motion, although the basic principles still apply. 4FH7 (SFAA) Any object maintains a constant speed and direction of motion unless an unbalanced outside force acts on it. 4FH8 (SFAA) 1993 Version of the Benchmarks Statements By the end of the 12th grade, students should know that The change in motion of an object is proportional to the applied force and inversely proportional to the mass. 4FH1 All motion is relative to whatever frame of reference is chosen, for there is no motionless frame from which to judge all motion. 4FH2 Accelerating electric charges produce electromagnetic waves around them. A great variety of radiations are electromagnetic waves: radio waves, microwaves, radiant heat, visible light, ultraviolet radiation, x rays, and gamma rays. These wavelengths vary from radio waves, the longest, to gamma rays, the shortest. In empty space, all electromagnetic waves move at the same speedthe speed of light. 4FH3 In the current version of Benchmarks Online, the second and third sentences of this benchmark have been moved to grades 6-8 and recoded as 4FM8 . Whenever one thing exerts a force on another, an equal amount of force is exerted back on it. 4FH4 The observed wavelength of a wave depends upon the relative motion of the source and the observer. If either is moving toward the other, the observed wavelength is shorter if either is moving away, the wavelength is longer. Because the light seen from almost all distant galaxies has longer wavelengths than comparable light here on earth, astronomers believe that the whole universe is expanding. 4FH5 Waves can superpose on one another, bend around corners, reflect off surfaces, be absorbed by materials they enter, and change direction when entering a new material. All these effects vary with wavelength. The energy of waves (like any form of energy) can be changed into other forms of energy. 4FH6 G. Forces of Nature For a good many school years, force may be treated as the originator of motion, and an explanation of force itself may be postponed. But the force between a bat and a ball has an entirely different origin than that between the earth and the moon. In helping students broaden their understanding of the fundamental forces of nature, the emphasis should be on gravitational and electromagnetic forces. The general idea of universal gravitation and how weak it is compared to other kinds of forces is sufficient. Working out numerical problems adds little and is very likely to leave many students behind. The math is not hard but the units are baffling. A paradoxical idea for students is how weak gravity is compared to electric and magnetic forces. Gravity becomes appreciable only when very large accumulations of matter figure, such as that of a student and the entire earth. To students, gravitational forces seem strong compared to the trivial electric forces on dry hair charged by combing. But they can be led to see quite the opposite: The whole earth is required to pull a hair down by gravity, while only a small amount of charge is needed to force it up electrically against gravity. Electric and magnetic forces and the relationship between them ought also to be treated qualitatively. Fields can be introduced, but only intuitively. Most important is that students get a sense of electric and magnetic force fields (as well as of gravity) and of some simple relations between magnets and electric currents. Direction rules have little importance for general literacy. The priority should be on what conditions produce a magnetic field and what conditions induce an electric current. Diagrams of electric and magnetic fields promote some misconceptions about lines of force, notably that the force exists only on those lines. Students should recognize that the lines are used only to show the direction of the field. Kindergarten through Grade 2 The focus should be on motion and on encouraging children to be observant about when and how things seem to move or not move. They should notice that things fall to the ground if not held up. They should observe motion everywhere, making lists of different kinds of motion and what things move that way. Even in the primary years, children should use magnets to get things to move without touching them, and thereby learn that forces can act at a distance with no perceivable substance in between. Current Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Things near the earth fall to the ground unless something holds them up. 4GP1 Magnets can be used to make some things move without being touched. 4GP2 1993 Version of the Benchmarks Statements By the end of the 2nd grade, students should know that Things near the earth fall to the ground unless something holds them up. 4GP1 Magnets can be used to make some things move without being touched. 4GP2 Grades 3 through 5 The main notion to convey here is that forces can act at a distance. Students should carry out investigations to become familiar with the pushes and pulls of magnets and static electricity. The term gravity may interfere with students understanding because it often is used as an empty label for the common (and ancient) notion of quotnatural motionquot toward the earth. The important point is that the earth pulls on objects. Current Version of the Benchmarks Statements By the end of the 5th grade, students should know that The earths gravity pulls any object on or near the earth toward it without touching it. 4GE1 Without touching them, a magnet pulls on all things made of iron and either pushes or pulls on other magnets. 4GE2 Without touching them, an object that has been electrically charged pulls on all other uncharged objects and may either push or pull other charged objects. 4GE3 1993 Version of the Benchmarks Statements By the end of the 5th grade, students should know that The earths gravity pulls any object toward it without touching it. 4GE1 Without touching them, a magnet pulls on all things made of iron and either pushes or pulls on other magnets. 4GE2 Without touching them, material that has been electrically charged pulls on all other materials and may either push or pull other charged materials. 4GE3 Grades 6 through 8 The idea of gravity8212up until now seen as something happening near the earths surface8212can be generalized to all matter everywhere in the universe. Some demonstration, in the laboratory or on film or videotape, of the gravitational force between objects may be essential to break through the intuitive notion that things just naturally fall. Students should make devices to observe the magnetic effects of current and the electric effects of moving magnets. At first, the devices can be simple electromagnets later, more complex devices, such as motor kits, can be introduced. Current Version of the Benchmarks Statements By the end of the 8th grade, students should know that Every object exerts gravitational force on every other object. The force depends on how much mass the objects have and on how far apart they are. The force is hard to detect unless at least one of the objects has a lot of mass. 4GM1 The suns gravitational pull holds the earth and other planets in their orbits, just as the planets gravitational pull keeps their moons in orbit around them. 4GM2 Electric currents and magnets can exert a force on each other. 4GM3 Electrical circuits require a complete loop through which an electrical current can pass. 4GM4 (NSES) A charged object can be charged in one of two ways, which we call either positively charged or negatively charged. Two objects that are charged in the same manner exert a force of repulsion on each other, while oppositely charged objects exert a force of attraction on each other. 4GM5 (BSL) 1993 Version of the Benchmarks Statements By the end of the 8th grade, students should know that Every object exerts gravitational force on every other object. The force depends on how much mass the objects have and on how far apart they are. The force is hard to detect unless at least one of the objects has a lot of mass. 4GM1 The suns gravitational pull holds the earth and other planets in their orbits, just as the planets gravitational pull keeps their moons in orbit around them. 4GM2 Electric currents and magnets can exert a force on each other. 4GM3 Grades 9 through 12 Students should now learn how well the principle of universal gravitation explains the architecture of the universe and much that happens on the earth. The principle will become familiar from many different examples (star formation, tides, comet orbits, etc.) and from the study of the history leading to this unification of earth and sky. The quotinversely proportional to the squarequot aspect is not a high priority for literacy. Much more important is escaping the common adult misconceptions that the earths gravity does not extend beyond its atmosphere or that it is caused by the atmosphere. Study of the nature of electric and magnetic forces should be joined to the study of the atom. What is likely to surprise many students is how much more powerful electromagnetic forces are than the gravitational forces, which are negligible on an atomic scale. Some students may have trouble seeing mechanical forces, such as pushing on an object with a stick, as being produced by electric charges on the atomic scale. It may help for them to recognize that the electric forces they do observe commonly (such as quotstatic clingquot) result from extremely slight imbalances of electric charges. As students come to believe in the actionreaction principle, they will expect forces to be mutual. Current Version of the Benchmarks Statements By the end of the 12th grade, students should know that Gravitational force is an attraction between masses. The strength of the force is proportional to the masses and weakens rapidly with increasing distance between them. 4GH1 Electric forces acting within and between atoms are vastly stronger than the gravitational forces acting between the atoms. At larger scales, gravitational forces accumulate to produce a large and noticeable effect, whereas electric forces tend to cancel each other out. 4GH2a At the atomic level, electric forces between electrons and protons in atoms hold molecules together and thus are involved in all chemical reactions. 4GH2b Electric forces hold solid and liquid materials together and act between objects when they are in contactas in sticking or sliding friction. 4GH2c Most materials have equal numbers of protons and electrons and are therefore electrically neutral. In most cases, a material acquires a negative charge by gaining electrons and acquires a positive charge by losing electrons. Even a tiny imbalance in the number of protons and electrons in an object can produce noticeable electric forces on other objects. 4GH3 In many conducting materials, such as metals, some of the electrons are not firmly held by the nuclei of the atoms that make up the material. In these materials, applied electric forces can cause the electrons to move through the material, producing an electric current. In insulating materials, such as glass, the electrons are held more firmly, making it nearly impossible to produce an electric current in those materials. 4GH4ab At very low temperatures, some materials become superconductors and offer no resistance to the flow of electrons. 4GH4c Semiconducting materials differ greatly in how well they conduct electrons, depending on the exact composition of the material. 4GH4d Magnetic forces are very closely related to electric forces and are thought of as different aspects of a single electromagnetic force. Moving electrically charged objects produces magnetic forces and moving magnets produces electric forces. 4GH5ab The interplay of electric and magnetic forces is the basis for many modern technologies, including electric motors, generators, and devices that produce or receive electromagnetic waves. 4GH5c The nuclear forces that hold the protons and neutrons in the nucleus of an atom together are much stronger than the electric forces between the protons and electrons of the atom. That is why much greater amounts of energy are released from nuclear reactions than from chemical reactions. 4GH6 Electric currents in the earths interior give the earth an extensive magnetic field, which we detect from the orientation of compass needles. 4GH7 (SFAA) The motion of electrons is far more affected by electrical forces than protons are because electrons are much less massive and are outside of the nucleus. 4GH8 (BSL) 1993 Version of the Benchmarks Statements By the end of the 12th grade, students should know that Gravitational force is an attraction between masses. The strength of the force is proportional to the masses and weakens rapidly with increasing distance between them. 4GH1 Electromagnetic forces acting within and between atoms are vastly stronger than the gravitational forces acting between the atoms. At the atomic level, electric forces between oppositely charged electrons and protons hold atoms and molecules together and thus are involved in all chemical reactions. On a larger scale, these forces hold solid and liquid materials together and act between objects when they are in contactas in sticking or sliding friction. 4GH2 There are two kinds of chargespositive and negative. Like charges repel one another, opposite charges attract. In materials, there are almost exactly equal proportions of positive and negative charges, making the materials as a whole electrically neutral. Negative charges, being associated with electrons, are far more mobile in materials than positive charges are. A very small excess or deficit of negative charges in a material produces noticeable electric forces. 4GH3 In the current version of Benchmarks Online, the first and second sentences of this benchmark have been moved to grades 6-8 and recoded as 4GM5 . Different kinds of materials respond differently to electric forces. In conducting materials such as metals, electric charges flow easily, whereas in insulating materials such as glass, they can move hardly at all. At very low temperatures, some materials become superconductors and offer no resistance to the flow of current. In between these extremes, semiconducting materials differ greatly in how well they conduct, depending on their exact composition. 4GH4 Magnetic forces are very closely related to electric forces and can be thought of as different aspects of a single electromagnetic force. Moving electric charges produce magnetic forces and moving magnets produce electric forces. The interplay of electric and magnetic forces is the basis for electric motors, generators, and many other modern technologies, including the production of electromagnetic waves. 4GH5 The forces that hold the nucleus of an atom together are much stronger than the electromagnetic force. That is why such great amounts of energy are released from the nuclear reactions in the sun and other stars. 4GH6 During the development of Atlas of Science Literacy, Volume 2. Project 2061 revised the wording of some benchmarks in order to update the science, improve the logical progression of ideas, and reflect the current research on student learning. New benchmarks were also created as necessary to accommodate related ideas in other learning goals documents such as Science for All Americans ( SFAA ), the National Science Education Standards ( NSES ), and the essays or other elements in Benchmarks for Science Literacy ( BSL ). We are providing access to both the current and the 1993 versions of the benchmarks as a service to our end-users. The text of each learning goal is followed by its code, consisting of the chapter, section, grade range, and the number of the goal. Lowercase letters at the end of the code indicate which part of the 1993 version it comes from (e. g. 8220a8221 indicates the first sentence in the 1993 version, 8220b8221 indicates the second sentence, and so on). A single asterisk at the end of the code means that the learning goal has been edited from the original, whereas two asterisks mean that the idea is a new learning goal. Copyright copy 1993,2009 by American Association for the Advancement of Science
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