Bumper cars are a traditional ride at many amusement parks and county fairs. Building model bumper cars can teach students about acceleration and motion. You can find some construction materials at home; you will need to purchase others to provide a motorized vehicle. Determine the size of the vehicle and how many other students will be participating before beginning. Some radio controls may interfere with each other when used in close proximity.

Purchase the remote control car chassis from a local hobby shop or online. Include the wheels and axles with the chassis. Assemble as necessary according to the package directions.

Measure the space between the wheels across the chassis and between the front and back wheels. Subtract ¼ inch from each side. Cut a square from the small cardboard cereal box to fit these dimensions. Lay the resulting rectangle on top of the chassis and move the car to ensure none of the wheels rub on the template.

Remove the cardboard template. Build the car body with Lego pieces on top of this cardboard template. The simplest car body pattern is to build a square that fits onto the template. Alternate bricks in each row so that you create a "brick wall" pattern.

Place both the template and the body on the chassis, once you have completed the body, to verify the car will move without anything rubbing on the wheels. The body must be at least 4 inches taller than the wheels to provide space for the bumper.

Glue the Lego body to the cardboard template. Allow the glue to dry completely before gluing the template and body to the chassis.

Blow up the animal balloon so that it is long enough to wrap around the body of the car and tie the ends together to form a tight "bumper." Animal balloons, frequently used by clowns to make animals or other balloon shapes, are long and thin. Do not over-inflate the balloon as it may pop on impact. Do not glue in place; tie tightly enough that it does not move.

Test the vehicle by bumping into the wall to verify everything stays in place and the balloon does not rub against the tires.