The document describes how to build a catapult out of simple materials like craft sticks, rubber bands, and glue to launch bottle caps as part of a science project replicating the Angry Birds game. It explains that a catapult is a type of third class lever that uses effort applied in the middle to lift a load on the opposite side of a fixed fulcrum. The catapult is then used to launch bottle caps at stacked glasses in a game similar to Jenga.