The lesson is scaffolded to even the most basic level, and the scaffolds can easily be adjusted for differentiation. The folder contains guided notes (in multiple formats), PowerPoint and homework. Here I introduce the basic concepts and mathematics of spring and gravitational potential energy. Before doing this lesson, you need to go get a racquetball, cut it in half, flip the half inside out and set it on a table. Wait a bit, and watch what happens. Your students will be as excited as you are.