Materials (per person)
- chipboard (8 1/2 x 11 sheet)
- wide container partially filled with water (e.g., kiddie pool, bathtub, underbed storage container, wallpaper tray)
- duct tape
- 2 paper cups (8 ounce or larger)
- 5 rubber bands
- scissors
- towels (paper or cloth)
- 4 straws
- washers (1-inch or larger)
- 4 wooden skewers
Your Challenge
Design and build a boat that paddles itself across a container of water using a rubber band as its power source.
Brainstorm & Design
Look at your Materials and think about the questions below. Then sketch your ideas on a piece of paper or in your design notebook.
- How can you use these Materials to make a boat that floats well?
- How will you attach a rubber band and paddle to your boat?
- How big a paddle do you need so that it reaches the water and drives the boat?
- How will you make sure your boat doesn't sink, tip, or roll over?
Build, Test, Evaluate & Redesign
Use the Materials to build your paddleboat. Then test it by winding it up, putting it in the container of water, and releasing it. When you test, your design may not work as planned. The saying, "If at first you don't succeed, try, try again," is at the heart of the design process. Testing a design and then revising it based on what you've learned is a key to success. Study the problems and then redesign. For example, if your paddleboat:
- tips—Add some weight to the bottom of the boat to help keep it upright.
- has a warped paddle—Think of some ways to waterproof the paddle.
- has a paddle that hits the frame holding it—See if moving the rubber band makes a difference. Also consider changing the size of the frame or the paddle.
- has parts that bend when the rubber band is wound tight—Make sure parts are taped on securely. Also, see if moving the rubber band makes a difference. The closer it is to the boat, the harder it will be to bend things. Finally, find ways to add support to any parts that bend.
- doesn't make it across the container—Experiment with ways of storing up more energy. Your boat moves by changing stored energy (potential energy) into motion energy (kinetic energy). The more you wind the rubber band (or the more rubber bands you use), the more potential energy you store. When you let go, this potential energy turns into kinetic energy, and the boat moves.
