Materials
Balloons, all the same size2 pieces of smooth string, each at least 10' (3 m) long
Masking tape2 wooden chairs1" (2.5 cm) piece of large plastic drinking straw, 1 per balloon
Instructions
1. Tie one end of each string to the back of each chair.
2. Explain that as the air rushes out of a blown up balloon, it will push the balloon in the opposite direction.
3. Blow up two balloons to approximately the same size. Pinch the ends closed but do not tie off. Tape a piece of plastic drinking straw to the side of each balloon.
4. Thread the untied end of the string through the straw so that the balloon is close to the chair. Make sure that the untied end of the balloon is facing away from the chairs.
5. Hold the strings taut. At "ready, set, go," release the balloons. Which balloon goes farthest?6. If one string is held horizontally, while the other string is held at an ascending angle, which wins? If one string is held horizontally, while the other string is held at a descending angle, which wins? If the strings are held at the same level and the second balloon is blown up to twice the size of the first balloon, which wins? After each experiment, ask the children why they think the results they observed happened.
