A bit of fun.
You will need:
A balloon, scissors, sticky tape, string and a drinks straw.
Thread the string through the straw and pin the ends up to make a washing line. Blow up the balloon, but don't knot the end, and tape it to the straw (don't tape the ends of the straw, they need to be free). Leave go of the balloon and it will fly along the string! Great fun!!
Try adding paper fins, feathers, streamers etc for added excitement/speed.