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UM A4 Video Clip 1: Group 1 tests a group of magnetized nails
Group 1 works on STEP 3 of Exploration #1. They investigate what happens when two of the magnetized nails are turned around. While Amy does the experiment Dawn and Kris predict what they think would happen. The result disagrees with their prediction but they quickly explain it in terms of 'canceling out'.
UM A4 Video Clip 2: Group 3 makes sense of a simulator movie
After having watched the movie in which simulator magnets get arranged randomly (STEP 4) the group makes sense of the result in terms of how the magnets are interacting with each other. They then discuss how to arrange a large number of magnets to produce strong and weak magnetic effects (STEP 5).
UM A4 Video Clip 4: Group 3 tries to demagnetize a nail
In STEP 6 of Exploration #2 the group tries several different ways to demagnetize a nail. They eventually succeed (after a suggestion from their instructor). However they do not seem to make a strong connection to how any of their suggestions could be framed in terms of any model. Note that the instructor misses an opportunity to prompt them to think more deeply when Faith suggests 'burning' the nail. (They will actually see this done in a homework extension.)
UM A4 Video Clip 5: Three groups present their final models
Group 9 presents their final model in the class discussion at the end of the activity. Then Groups 7 and 1 do the same. Seven of the eight groups in this class have a final model that is of the 'alignment' type. However Group 7's version is interesting in that they have found a way to account for their supposed observation that the cut ends of magnetized nails seem to be weaker than the non-cut ends. (The class later checked this result and found it not to be so.)
UM A4 Video Clip 6: Group 3 presents a different type of model
Group 3 is the only group in this class to not have an 'alignment-type' final model. Instead they have come up with a quite sophisticated modification of their previous 'ordered columns of individual poles' model to explain what happens when a magnetized nail is cut. Others in the class have trouble understanding it and ask questions.
UM A4 Video Clip 7: Some groups discuss the issue of 'cutting' particles
In the group presentation Faith (Group 3) claimed that all the models presented had faults. Another student asks her to explain the problem with the alignment model and Niki explains her issue with cutting the tiny magnets when the nail is cut. Grace and Susan (Group 7) rationalize how this could happen and the model could still work.
UM A4 Video Clip 1: Group 1 tests a group of magnetized nails