How to Make a Rubber Band Powered Boat

Build your own speedy boat using a rubber band and simple household materials to explore the science of potential energy.

1. Prepare the propeller. Cut your thick plastic or lid into a rectangle about 3 inches by 5 inches. This will be your propeller. Ask a grown-up to help you cut a small notch into the center of both short ends of the rectangle so the rubber band can sit securely.
2. Attach the rubber band. Slide your two rubber bands onto the back of the plastic water bottle. They should wrap around the bottle horizontally, sitting about one inch from the end. Make sure they are tight enough that they don't slip off.
3. Install the propeller. Slide your plastic propeller rectangle in between the two rubber bands. The rubber bands should rest inside the notches you cut earlier. This creates the tension needed to spin the propeller.
4. Test your boat. Twist the propeller around and around to wind up the rubber bands. Hold the propeller in place with your finger, place the boat in a bathtub or a pool, and let go to watch it zoom forward.