This unit develops concepts of energy and engineering through design, construction and testing of an elastic powered vehicle, a wind-up. To operate a wind-up, a user stores potential energy in a rubber band, and then releases it, converting the energy to kinetic form, and thereby powering the vehicle. Students begin by looking at the operation of a sample wind-up, and then think about how to make their own. As they create wind-ups, they record issues that arise, learn about troubleshooting, and write their own troubleshooting guides. They make more wind-ups and learn how to experiment with them. Finally they develop and test instruction manuals, and present the results of their work.