# Day 39

Today I am beginning the acceleration unit with my students. Because they just took an exam, and the material is cumulative, I had them begin by doing a quick whiteboard warm up where they calculate the displacement of  a constant-velocity object from its position graph . I also had them plot the velocity as a function of time.  We did this for an object travelling in the positive direction and for one travelling in the negative direction.

Next, we moved into what I like to call the “warm-up” part of the lab. I showed them a marble rolling down a tilted whiteboard and asked them what was different about the marble vs. a constant velocity buggy. The answer they gave was the obvious and correct one, namely that it is speeding up.

I then gave them 20 minutes to prove this to be the case.

A number of interesting things happened. Students tried to show that the marble was speeding up by treating the angle of the incline as an independent variable. We  then had interesting discussions about what exactly they were showing with this experiment.

I decided to have them share out on a blog:

http://goo.gl/TTvqKj

Unfortunately, this activity took a little longer than I thought, and I had about 10 minutes to wrap up. I decided to give them a preview of the lab that we will be doing next time, whicvh I will discuss in Day 41’s post.