In this activity from Bill Nye, students create a simulator (using a paper plate, marble, and scissors) to investigate how forces (push and pull) keep objects moving in a circular orbit. This process is similar to how Earth’s gravity keeps satellites and shuttles moving with its direction constantly changing. This easy to perform experiment allows students to examine the differences that closed and open orbits play on moving objects. Though it is not explicitly stated in the instructions, students would benefit from making predictions between both models and then test their hypothesis as they move on to subsequent trials.