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Experiments to Do With a Balloon

Balloons are good for more than decorations. A balloon and other simple materials can create kid-friendly experiments that teach everything from thrust to the properties of water to centripetal force. Balloons provide a vivid prop to demonstrate these lessons, so kids can have fun while learning. Make sure you understand the basic science behind the experiments before performing them, but don't hesitate to look up your children's questions with them if you don't know the answers.

Balloon Rocket
- Teach your child about thrust with a balloon rocket. Gather a 10-foot or longer piece of string, a plastic drinking straw, tape and a balloon. Thread the straw onto the string and tie one end off on a chair, doorknob, post or other stationary object. Pull the string taut and tie it off at an equal height. Blow up the balloon, hold the end closed and tape it to the straw. Let go of the end to send the balloon rocket flying. Explain that this demonstrates thrust, the force that propels objects like rockets. In this case, the air in the balloon creates the thrust. Experiment with different degrees of thrust --- for example, blowing up the balloon more or less, or tying one edge of the stringer higher and sending the rocket up and down the string.
Fireproof Balloons
- Blow up one balloon and tie off the end. Insert a funnel into another balloon and pour in about 1/3 cup of water. Blow up that balloon and tie it off. Ask your child what will happen when you hold a flame to each balloon. Light a match and, holding the empty balloon by the tie, hold the match to the balloon. It will pop quickly. Light another match and hold it in the same way to the water balloon. It won't pop. Ask your child to guess why. In this case, the water absorbs the flame's heat, keeping the match from heating the balloon as much. The empty balloon doesn't have this protection, so the latex, which is fragile, heats quickly and breaks, popping the balloon.
No-Blow Up Balloon
- Gather a balloon, funnel, baking soda, white vinegar and an individual-sized soda bottle, about 20 oz. in capacity. Pour about 3/4 cup of white vinegar into the soda bottle. Insert the funnel into the balloon and spoon in several teaspoons of baking soda. Spread the balloon opening over the neck of the bottle, but don't let the baking soda escape. Then straighten the balloon, allowing the baking soda to fall into the vinegar. Stand back and watch the balloon expand from the gas created from the combination. Explain to your child that some things, when combined, create a reaction --- for example, hydrogen and oxygen make water. Similarly, baking soda and vinegar make a gas, and that gas is like air that blows up the balloon, just like blowing it up by your mouth does.
Spinning Coin
- Gather a balloon, preferably one that is clear or easy to see through when inflated, and a small coin, like a dime or penny. Insert the coin into the balloon, blow it up and tie it off. Hold the balloon upside down and rotate it quickly in a circle parallel to the floor. The coin may flop around a bit, but will soon start spinning on its edge around the inside of the balloon. Keep rotating the balloon, and the coin will keep going. This is an example of centripetal force, where an object in motion over a curved surface seeks the center point. The coin spins around the balloon in an effort to find that center.

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