NextGenPET Instructor Resources

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UM L4 Video Clip 1: Students in class discuss their revised models from end of UM L3

The instructor calls on some students to discuss their revised models that they had developed at the end of the previous lesson. First a student from Group 8 describes what the entities are like inside the unmagnetized nail and then talks about what happens to them when the nail is magnetized. She then explains how that model can account for what happens when a magnetized nail is cut anywhere along its length.

UM L4 Video Clip 2: Student discusses her group's revised model from end of UM L3

This video is from a previous semester. A student uses the document camera to describe her group's revised model at the end of UM L3.

UM L4 Video Clip 3: Group 1 discusses CQ 4-2

Before voting on CQ 4-2 Group 1 discusses their predictions. Veronica thinks it's the same situation as with the previous demonstration (from page M-31) with the magnetized nails in front of the compass. Therefore she would choose C. Tiffany thinks the magnets would attract each other and would also attract the paper clips—just like when the magnets had their N-Poles pointing the same way. So she would choose A. The other two students are also split between A and C.

UM L4 Video Clip 5: Class discusses reasons for choice A in CQ 4-2

After the vote on CQ 4-2 the instructor points out that there seem to be two different ways of thinking. He mentions that doing the experiment will help students decide but he first wants some students in the class to articulate the two different ideas. He begins with those who chose A (same number of paper clips will be picked up). The first student argues that since the paper clips are unmagnetized the polarity of the magnets (N or S Pole) shouldn't have an effect on the number of paper clips picked up. They should still pick up the same number. Another student further supports that argument by mentioning that they did an experiment earlier (in UM L2) with the magnet and paper clip that would support choice A. In that case both ends of the magnet picked up the paper clip.

UM L4 Video Clip 6: Class discusses reasons for choices C and A in CQ 4-2

The instructor calls on students who chose C (fewer paper clips). Veronica from Group 1 expresses her uncertainty. She explains why she had chosen C (many fewer paper clips would be picked up): that the oppositely directed magnets held together would cause the 'force of magnetism' to stay there and not be able to 'move forward' and pick up any paper clips. Another student argues against that view emphasizing that each magnet would still pick up paper clips (choice A). The next student says she understands the two views but argues for choice A (since the paper clips would be picked up by either Pole). The following student then agrees with Veronica but argues that there would be both repelling and attracting occurring which will cancel out the effects so no paper clips would be picked up (choice C).

UM L4 Video Clip 8: Group 1 discusses their final model

Group 1 spends a lot of time (about seven minutes; this video clip has been edited) discussing what their final model should be. It is very interesting to see how they draw on what they had learned previously to develop their final model.

At the beginning Veronica asks the group for their ideas for a 'final model.' First Tiffany makes a brief comment. Then Lauren suggests what is happening in the nail is like 'this pivot thing'—the simulation movie they had just seen where a magnet on a pivot rotates as another magnet is moved across the screen from left to right. She thinks an entity inside the nail rotates inside the nail. Tiffany returns (briefly) to the idea of the N and S entities not being grouped together but she is unsure what happens when the nail is rubbed.

Veronica jumps in and points to the simulation pictures in the student materials (page M-33) as a helpful way of thinking about what happens inside the nail. She sketches a nail on top of the magnet arrangement and helps others see the connection. Lauren then realizes that you can then split it anywhere and it still works (is still magnetized). Veronica suggests that the N-S entities must be grouped to explain what happens. Tiffany is still unsure. But then Lauren mentions that when you rub the nail they (the entities) all rotate and she is excited because now the pivoting issue makes sense to her. She explains it to the group (with supporting help from Veronica) and is 'so happy.'