I use this activity as an introduction to kinematics. Students must determine what data is required to measure the speed of their racer. Students discover that they already know quite a few physics principles. The rocket racer is also a good demonstration for Newton's Third Law of Motion. Students should design their racer and then trace their designs onto the Styrofoam tray.
Students can either use scissors to cut out their design or snap out the parts from the tray.
If a pen is pressed deeply into the tray to outline the parts, the pieces should snap out. Stretch the balloon by blowing it and letting the air out. Tape the balloon to the short end of a flexible straw. Construct a track on the floor marked off in 10 cm increments. Blow up the balloon through the straw.