Have your students duplicate one of the most famous experiments in physics. Have them prove acceleration = distance/time2. Students measure time using a water clock (Galileo's invention). They use the water clock to time the roll of a steel ball down an inclined plane. Then they calculate the acceleration and compare the acceleration at different distances. Kit includes the track assembly, stop block, plastic tube assembly, funnel, steel ball, and instructions. Ring stands and support rings sold separately.