! Common!Writing!Assignment:!Science!!

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HS:!Physics!! BPS!Science!CWA!materials!2016!!Adapted!from!Active!Physics,!K.!McNeill,!teachers!&!others!

Ohm’s&Law&CWA&

The!Ohm’s!Law&CWA!is!a!lesson!specific!assessment.!!The!overarching!question!is:!!How!do!voltage!and!resistance!each!relate!to!electric!current!in!a!circuit?!!The!following!handouts!are!included:!

• Prompt!• Sample!student!response!• Actual!student!response!

!Students!should!be!provided!the!prompt,!which!includes!the!question!as!well!as!data!necessary!to!answer!the!question.!!A!sample!student!response!is!included!as!well!as!actual!student!work.!!Either!the!CWA!Common!Scoring!Rubric!or!the!Old!Science!CWA!Rubric!can!be!used!to!score!the!responses.!

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Ohm’s&Law&&

Claim/Evidence/Reasoning&(CER)&Writing&Assignment&&

&Scientific&Question:!How!do!voltage!and!resistance!each!relate!to!electric!current!in!a!circuit?!! ! !

As!part!of!your!answer,!state!whether!each!relationship!is!linear!or!nonRlinear.!

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Ohm’s&Law:&&Sample&Student&Response&&

Claim:&

Voltage!and!resistance!each!relate!to!electric!current!as!follows:!Increasing!voltage!causes!electric!current!to!increase!(current!is!directly!proportional!to!voltage)!and!increasing!resistance!causes!current!to!decrease!(current!is!inversely!proportional!to!resistance).!

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Evidence:&

In!experiment!1,!increasing!the!voltage!while!holding!the!resistance!constant!caused!the!current!to!increase!in!a!direct!(linear)!relationship.!

In!experiment!2,!increasing!the!resistance!while!holding!the!voltage!constant!caused!the!current!to!decrease!in!a!direct!(linear)!relationship.!

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Reasoning:&

As!such,!electric!current!is!directly!proportional!to!voltage!and!inversely!proportional!to!resistance.!!These!relationships!are!referred!to!as!Ohm’s!Law,!which!is!expressed!as:!

!Current = I = VoltageResitance

=VR=V 1

R!

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The!formula!is!a!linear!equation!when!either!V!or!R!is!constant,!as!was!the!case!in!experiments!1!and!2.!The!formula!indicates!that!current!is!related!linearly!to!V!and!1/R,!which!corresponds!to!the!straight!best!fit!graph!lines!from!the!experimental!data.!

clairn: write o stdtement (basei on your evidence and reasoning) that directly dnswers the scientific question.

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Reasonin g: Explain, using relevont science concepts you leorned, why your evidence bocks up yaur cloim.

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