How to start teaching physics

This morning we started a lab exactly the way I wanted.  Here’s how it went:

I gave each lab group two electronic thermometers, and a small an a large glass beaker.  I told them to put hot water in the small beaker and cold water in the large beaker.  What will happen when you submerge the small beaker into the large one?

They then had to actually do it, measure what happened, and predict what would happen if they changed something, for example the amount of water in one of the containers.

It was fantastic because I didn’t give them any physical model beforehand.  They had to use all of their prior knowledge from their everyday lives to make those predictions, and most of them were surprised by how much they were able to predict just by using their own reasoning.

Next time I’ll give them the model – entropy and energy, dE=T dS or some simplified version of it, with the 1st and 2nd laws of thermo, and they’ll apply them to the experiment again.

This is about as good a starting point as I can think of.  Simple, fundamental laws, and a simple, familiar apparatus.  If we can get a grasp of how temperature, energy and entropy are related, we will have our first proper physics model.  After that, we can talk about materials, latent heats, gas laws and engines as the year goes along.  Can’t wait to see how it turns out!

You know, teaching is like judo: the more you teach, (the more “material you cover”), the less they learn.  It’s incredible how much learning can happen when you do almost no teaching!