Let's start by setting up the arena for the race. You'll need a long piece of string and a drinking straw. Make sure that the straw can run easily along the string. Tie one end of the string to the finishing post, which could be a door handle or a bath tap, for example. Run the straw along the string to make sure that it has a knot-free run. Now take a balloon, and blow it up. Don't be worried about asking for help with this, as balloon blowing is notoriously difficult! Don't tie the neck of the balloon, just keep it in place by tying it around a pencil and gripping it in place with a plastic clothes peg. Now tape the straw to the middle of the balloon, so that it's evenly balanced. When you've done that, carefully remove the clothes peg but hold the neck of the balloon - otherwise the air will escape before you're ready! Then pull the string tight, let go of the balloon and watch it race down the string. Pretty good eh? Well that's the basic principle, but there are ways it can be improved and refined... For example: You could use nylon thread instead of string to reduce friction; You could use two balloons stuck together; And you can improve the appearance with streamers and decoration!