##
* *Reflection: Complex Tasks
Electromagnetism Follow Up - Section 3: Conclusion

As you can see from the video, a second day to clarify a few ideas did not have the desired result. I think I left this lesson too open to confounding variables, which left me trying to get my class to see that there was, in fact, no relationship between length of wire, and number of paperclips picked up. My students were not ready to look at a scatter plot and see there was no clear relationship between variables. I was trying to foster their curiosity (Do you think it might make a difference if there is a space between wraps?) when I should have been helping them isolate a variable. What I should have done was to ensure everything besides the number of wraps was being done in the exact same way from the beginning, including wrap direction, size of gaps, and overlap. If everyone had the same length of wire, and wrapped it 20, 40, 60, and 80 times around the bolt, it would have been easy to see the results.

*Proving the Null Hypothesis*

*Complex Tasks: Proving the Null Hypothesis*

# Electromagnetism Follow Up

Lesson 13 of 14

## Objective: SWBAT explain factors influencing the strength of an electromagnet.

*50 minutes*

#### Introduction

*10 min*

I began by having students write the focus question, "How can you use evidence to support your claim about electromagnets?" in their science notebooks. I then asked them what conclusions we made about electromagnets in our previous lesson. Some students claimed the length of the wire influenced the strength of the magnet, and some said it was the number of wraps. I had them go back and look at their notes, and figure out what variable we changed in the previous electromagnet lesson (the number of wraps). I pointed out that we never measured a single wire, so we had no data support the claim that the longer the wire, the greater the strength of the electromagnet.

*expand content*

#### Engagement

*30 min*

I asked them to think about how we could find out how the length of the wire affects the strength of the magnet, and this became our new experimental question. I guided them to understand how we could only change the length of the wire and not the number of wraps by keeping the number of wraps consistent. We chose 40 wraps, sort of arbitrarily.

I gave an expectation that each group was required to test three different lengths of wire, at two trials each wire. Each group then sent up a representative to get a bold and a length of wire, and they began wrapping the bolt, same as yesterday. I had to remind them to stop at 40 because they kept coming up with all of the wire wrapped around the bolt. Really long wires should have a lot of extra sticking out. They then came up in groups, same as yesterday, to see how many paper clips they could pick up, and to record their data.

*expand content*

#### Conclusion

*10 min*

As each group finished, I had them come up to the document camera, and add their data to the class Data Table. After all groups were done, I had one student plot the results in a scatter plot diagram. The purpose of the plot was to help students see that there was no relationship between the length of the wire and the number of paperclips picked up, proving that the number of wraps form the previous experiment was the main thing affecting the strength of the magnet. Unfortunately, you can see in the video that I was the only one who could see that clearly.

#### Resources

*expand content*

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- LESSON 1: Electricity and Magnetism Pretest
- LESSON 2: Building Circuits
- LESSON 3: Insulators and Conductors
- LESSON 4: Building Series Circuits
- LESSON 5: Parallel Circuits
- LESSON 6: Human Circuit Models
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- LESSON 14: Magnet Engineering Design Challenge