Originally, I used to do both parts of this lab in one complete lab. I found that my students spent most of their time confused saying things like “Which collision is this again?” so I revamped the one lab and split it into two separate labs. In fact, I do these two labs on two separate days. I have found that for my students this small break in time between the two labs makes them more able to fully comprehend the differences between elastic and inelastic collisions.