A little note on what I am teaching right now, and my general method. We are beginning the semester with the Gas Laws. The teacher I am replacing said she likes to start with them because they are fun. The are fun. I hadn’t realized quite how fun they are.
I started with an overview of the kinetic molecular theory of gases. I want them to understand the concepts and be able to picture the relationships in their head before I give them the equations. I don’t intend to skimp on the math, however. There are some advanced math students, and some students who love the math in chemistry, but I don’t think they’ll suffer or learn less well by picturing things first. I hope it helps the students who love math a little less to have a good model for predicting and interpreting the numbers.
I have all their balloon drawings back. I wanted to see their prior knowledge and misconceptions about gases, so I had them draw three pictures of a balloon and three temperatures, with labels and explanations. They are very interesting. Pretty much everyone got that hot gases are moving faster, and slow gases more slowly (we talked about that a lot), and they mostly understood that the molecules of cooler gases are closer together. What was interesting was that many of them didn’t change the volume of the balloon to change the density of the gas, they changed the amount of gas molecules in the balloon. I also had a significant minority who put all the gas molecules at the bottom of the balloon for the cold one, in the middle for the room temp. one, and at the top of the balloon for the hot one. Some students had the hot balloon rising and the cool balloon sinking. Very interesting. I am planning to photocopy some of the really good ones, and some of the ones with common misconceptions, and give them to the students in groups for them to come up with a grading rubric. I will block out all identifying information. I will also do it near the end of the unit, because this question will be on the test. I want them to have a chance to learn to evaluate a complete, accurate, scientific answer, and hopefully to generate some discussion. The first period will not discuss anything in groups (except for one table), and third period is great at it. I don’t know if it is all up to the time of day.
I will also scan some of the interesting ones for my e-portfolio, and I can compare them with the test results.
