🚗 Balloon-Powered Car

When you let go of a balloon, the air rushes out the back and pushes the car forward. Push one way, go the other way! (This is Newton's third law: every action has an equal and opposite reaction.)

• Build about 20 reusable cars.
• Tape a straw exhaust on each car.
• Tape a track, marked every foot.

Crew for prep: 2 people, about 1.5 hr. Prep happens on the day, from 12:15.

During the event: 2 volunteers. Setup about 20 min. One helps at the start line, one measures or runs the leaderboard

Tips

• Pre-build about 20 reusable car bodies: a toilet-paper-roll or cardboard body, straws taped on as axle holders, skewers as axles, and wheels (wooden wheels or pre-punched bottle caps). Kids don't build the chassis.
• Pre-tape a straw "exhaust pipe" to each car.
• The kid's job is to stretch a balloon over the straw, blow it up through the straw, set the car down, and let go.
• Make it a challenge with a taped track and distance marks every foot. "How far did yours go? What if you blow it up bigger?"
• Older kids can change one thing, like the wheel size, a second balloon, or the straw angle.

• Balloon pieces: choking risk under age 8.
• Ask about latex allergies.
• Keep the track clear of people.

• Two-lane drag strip with a finish line and a leaderboard ("fastest car of the night"). Add a balloon rocket on a long string across the blacktop for a showpiece.

• Wipe the table and put reusable items in your tote.
• Bag the trash and wash hands.
• Log anything borrowed so it can go back.