Balloon Rockets: What you need: Piece of yarn (or string) – cut to about 6 feet, thread on a straw and tie string to two chairs. Put tape on straw to attach a Balloon that has been blown up but has not been tied. Pull attached balloon to one side and let go! Experiment shows action and reaction. Kids will want to do over and over so be prepared to blow up a few balloons and have extra tape on hand. Link leads to step by step instructions with a photo tutorial.
Super easy rocket craft made from a balloon, a straw, a rubber band and some paper. I think kids will have a ball launching these! (Using balloons of various colors would make it a little easier for kids to keep track of their own rockets.)