Students can easily make simple catapults using popsicle sticks or taped paper cylinders held together with glue and rubber bands. A bottle cap glued to the throwing arm holds the projectile.
To make a catapult with popsicle sticks, bundle six popsicle sticks together with rubber bands. Attach one stick vertically to the center of the bundle with a rubber band looped over the top, sides and bottom of the vertical stick. Complete the frame with three more sticks, and glue a bottle cap to the end of the throwing arm. To increase the catapult's throwing power, glue another piece of popsicle stick to the back of the frame and loop a rubber band from it, under the frame and over the bottom of the throwing arm.
The paper catapult is similar but requires stabilized upright pieces on either side of the throwing arm. A rubber band looped around a horizontal cylinder between these uprights gives the throwing arm its power.