Human Circuit Models

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Objective

SWBAT describe electricity as the flow of electrons through a complete circuit.

Big Idea

How can we model how electrons flow?

Introduction

10 minutes

There is a widely held misconception that within a circuit, you have to wait for the electrons to get to the useful resistor before something happens.  The purpose of this lesson is to help students understand that everything inherently has electrons, and electricity comes from the flow of electrons.

I had my students write the focus question, "How can we model how electrons flow?" in their science notebooks, and complete the sentence"I think the electrons in in a circuit..."  I then asked them to take a moment to describe how they believe electrons work within a circuit to a shoulder partner.

Engagement

30 minutes

I had all of my students stand a in a circle.  I gave each of them a tile, and told them it represented an electron.  I explained that everything has electrons, but that conductors are things that give up their electrons more easily. I chose one student to represent a battery, and hung a sign on their neck reading battery. I gave them two tubs, one empty and one full of tiles.  I explained that when there is an imbalance in charges, having lots of extra electrons on one side, and none on the other, the electrons would flow in a circuit.  I told them to begin to pass their electrons into the empty tub. I made sure  they noticed that they always had electrons, but electricity was generated through the passing of electrons.

My students figured out right away that this was a short circuit.  I acknowledged that, and then asked them to explain how they know, and how they would fix it.  We needed a useful resistor, such as a light bulb.  We gradually expanded the circuit to include a switch, motor, and lightbulb.  I opened the switch when needed so we could discuss how the electrons were already "in the pipe."



Closure

5 minutes

To help connect the model to the idea it represents, I had my students write down what the tile and the people in the model represent.  Then I asked my students to reread their initial understanding about electrons.  I asked them to choose one of the following sentences to complete in their science notebooks.

"I used to think..., but now I know..." or "One question I still have about electricity is..."  (This freedom saves me from having to answer the "What if I don't have X?" concerns.)