Investigating forces with balloon rockets.
Straws (that will slide over string)
chairs (to tie string to)
1. Cut string ~3m and thread straw. Tie one end to chair.
2. Tie other end to another chair and pull chairs apart so string tight.
3. Blow up balloon and hold neck closed with paperclip.
4. Tape the balloon to the straw.
5. push balloon to one end of string with neck facing chair.
6. Take paperclip off - balloon will rocket along the string.