Pump a Number

Materials

beach balls in different sizes

Instructions

1. Show the children a deflated beach ball. Explain that you are going to use a
bicycle pump to push air into the ball.
2. Demonstrate pumping air into the ball, counting each time you pump.
3. Ask the children to guess how many pumps it will take to fill the ball. Fill the
ball and see how close the children's guesses were.
4. Pump air into beach balls of differing sizes. Ask the children to guess which
balls will need the most and least number of pumps.