In this problem, students draw models of what happens in a nail that gets magnetized. We anticipate that students who think of magnets as having a north/south polarization will model this as having the magnet with charges of one type on one side and the other on the side. Other options will include the nail as having charges that are "activated" by the magnet. Students also, we anticipate, will think of magnetic charges as similar to electric charges, where one charge can be added or removed from the magnet to give it an overall charge.

For teachers, we can imagine responses that take seriously the range of student ideas and imagine ways to test those ideas. Or that ask students to generate a list of how electrical and magnetic charges differ and use those to draft models that compare a charged object with a magnetized object.