Creating Controversy

We have recently begun our weather unit, which is different from a typical weather unit in science. The curriculum uses a main theme to tie several concepts together. In the weather unit, things like phase changes and the behavior of gases are related to weather, so the other day, we talked about proportions using rain gauges. This is the introductory question:

One class in particular really got into the discussion of this question. It was a little controversial - why do we measure rain in inches, rather than in cups, milliliters, or fluid ounces? Some students took a stand that the bucket would be the best because it would catch the most water. Other students were convinced that the beaker is the best because the sides are straight up and down. Does the size of the rain gauge really matter? After they started going back and forth a bit, they all got really confused and were puzzled by the question. I "made it rain" with a watering can into a beaker and a test tube, showing that they both collect the same height of water, even though one is much larger, because height is proportional to volume.

I was impressed with how much this little bit of controversy or confusion got the students engaged in the class. Some students were literally waving their hands, saying "Pick me!" because they wanted to participate in the discussion. I usually struggle to get more than a few students talking at the beginning of class. Note to self: if they aren't talking, introduce a little controversy.