Who wants to volunteer?

I gave my problem based lesson last Monday before Thanksgiving. I wanted to do a lesson that would incorporate what they will be learning shortly in the class: speed, velocity, acceleration, and forces. It was a two part lab, the first part we worked together as a group. I had three different balls, a ping pong ball, a tennis ball, and a four pound medicine ball. I asked for three volunteers (always my favorite part because every hand goes up even when they have no idea what’s going on). I had them each hold a ball at the same height and then we dropped them at the same time to see which one would hit the ground first. Most of them were pretty shocked to find out that they all hit at the same time and that mass has nothing to do with their acceleration which was fun. The second part of the lab was more hands on for them. We set up ramps at each of their tables with cars. We had them change the height of the ramps and measure the velocity and acceleration. They all did pretty well except keeping their attention afterwards was impossible unless I walked around and picked up the cars from them 🙂

The hardest part of this lab was getting them to relate these measurements and observations to the accelerations and forces. They understood quickly with the dropped balls that even though the accelerations were the same, the masses were different which changed the force. They were also able to understand easily that the main force acting on the balls is gravity. Once we got to the cars though, they struggled piecing together why the cars accelerations were different when the height changed. I had to go over the relationship between velocity and acceleration over again for every class (we had just gone over it at the beginning of class too), so they could see that if the velocity changes, the acceleration does also. Only one or two of them were able to see on their own that there was more than once force acting on it now also (specifically I was looking for them to see that friction slowed the cars down). These are relatively big new concepts though, so I wasn’t expecting them to all to be experts at it, I was just hoping for more retaining of information they had just learned five minutes ago.

Another difficulty I noticed is they don’t seem to understand the purpose of a hypothesis. When I asked them to write one, they could all tell me it was an if, then, because statement which was great. But they couldn’t actually fill in the blanks. And at the very end, they couldn’t tell you if the hypothesis was right or wrong! So I think I may be working with them on hypothesis more next semester. That’s a skill that I feel everyone should know, it’s the basis of science and research to learn to formulate questions from observations!

Overall, I felt it was pretty successful because each student walked away learning at least one thing new. They definitely need much more exposure to learning this way though, which I will make my goal for the rest of the year.