These classic siege weapons from the middle ages happen to be great tools for teaching physics, including lessons in force, energy, motion, and projectiles. When the projectile, called the bolt, is loaded into the crossbow, a rubber band is pulled backward and energy is stored in the stretched rubber band. A trigger then releases the bolt and the rubber band launches it through the air toward the target. Catapults are additionally medieval ballistic devices that use mechanical rubber bands and counterweights to fling projectiles into the air. In the beautiful, 32-page manual, build and experiment with five different types of crossbows in the ten-experiment set!