Cut a long piece of string, several feet long. This will act as your track for the launch. Thread the string through a wide straw, cut to 4" long.

Find an open area to tie or tape the two ends of the string. We found a good spot outside between trees, but you can also tie the string to two chairs inside.

Blow up the balloon and pinch the opening to keep the air inside. Use tape the secure the balloon to the straw.

From one end of the string, let go of the balloon and watch it zoom across!