Ms. Nancy had the children line up chairs on the far side of the room. She talked to them about thrust and how it make a rocket climb into outer space. (After the program, on our way home, I talked to the children about Newton's second and third laws. They found it interesting and started to ask all sorts of questions of what if and why.)
Once Ms. Nancy had explained the experiment, everyone became busy tying string to chairs. Out came the balloons and the children immediately began blowing them up. Moms' threaded the string through straws and children scurried to find tape. Rockets began to fly down the string and a few balloons around the room.
Everyone was busy testing which balloon worked best. The children readily changed out balloons. Of course they pulled the straws off the string, so moms' had to rethread the straws.
We had a great time with the balloon rockets!