I thought other physics teachers here might be interested in this browser-based educational application I wrote: http://www.lightandmatter.com/velocity/ . As you move the mouse up and down, it graphs its position, velocity, and acceleration. In the past I've had some classroom exercises that used this sort of thing, but I did them using ultrasound sensors. The ultrasound setup was flaky and time-consuming to set up during lecture, so I think this may work better. Here are a couple of sample activities: task 1 Your goal is to produce an x-t graph that looks like a staircase going down and to the right. Discuss with your group (a) how you would need to move the mouse in order to accomplish this, and (b) how the v-t graph would look. Now try it, and compare with your prediction. If your prediction was wrong, discuss why. task 2 Imagine -- but *don't do it yet* -- that you repeatedly wiggle the mouse up and down, doing it fast but smoothly. (You may actually find it physically smoother to move the mouse rapidly in a circle; the horizontal part of the motion will be ignored.) As a group, predict what the x-t, v-t, and a-t graphs would look like, then test your prediction.