I am currently a senior at Wartburg College and thinking back to my senior year of high school we worked on mousetrap cars. This is a fun activity for students to do or even for a teacher to show and have multiple designs ready to test with. The lever on the mousetrap has a sting tied to it and on one or both of the axels of the car. This creates a transfer of potential to kinetic energy that propels the car further. You can make longer arms, bigger wheels, add a rubber band around the wheels for added grip like a car tire, and a lot more variables. The website below is a link to Popular Mechanics that has a video from a former NASA engineer Mark Rober, he does a great job of explaining the physics behind mousetrap cars as well as a boat load of different cars that you can make.