Sometime a demonstration can show something quickly and easily, be tiny and simple, and yet still take the students by surprise. I steal my demonstrations from other teachers, websites, blogs, the IoP and very occasionally, I do something new in a lesson and find myself doing it forever. I have to admit, I am not great with practical work so it is rare indeed.
I use this demo when teaching about magnets, and it came about when I asked a class if they thought paperclips were made from a hard or a soft magnetic material. Then, of course, I had to find a way of showing them and I was quite surprised. However, I now use this demonstration to talk about induced magnetism. All you need are two paperclips and a magnet (it is wise, because my classes don’t wish to feel tricked, to show there is no attraction between the paperclips initially):
All I do is allow the paperclips to hang them from one end of the magnet and then ask what will happen when I remove them from the magnet. The students always think that the magnetism will go and they will separate. Well, so did I the first time.
If I am very gentle and slide the paperclips off the magnet, the two paperclips stay hanging from each other. Not only that, but I have a convenient, out of the way, ceiling hook, where I leave them until the magnetism goes. Which it doesn’t. If they are left unmolested, and mine often get blown by the wind, they can stay hanging for months. The students like to bet on how long they will last, and there is no doubt that I have induced magnetism in the paperclips by placing them close to the magnet.
The reflective physics teacher 