The Balloon Rocket is a simple, fun toy for indoor or outdoor toy that can be made from materials you probably have around the house. (You can teach some science concepts, too, if you would like.)
You will need:
Plastic drinking straw
10-25 ft. of fishing line or string
Long, tube-shaped balloon (all we had on hand this time were round balloons and it worked, although not as well as the long balloons)
Blow up a balloon. While keeping the end of the balloon pinched shut with your fingers, tape a straw to the balloon. I found that having someone help you with this makes it a lot easier. Then put some string through the straw, making sure that the open end of the balloon is facing backward from the way you want the balloon to go. Tie one end of the string to something like a chair.
Then let the balloon go. It will zip along the string like a rocket. You can do it over and over again by just leaving the balloon attached and blow it up while it is still attached.