Zoom-Zoom Balloon Rocket

What you need

• Painter's tape, 2 strips
• Balloon, 2 or 3
• String, 1 long piece
• Straws, 1
• Chairs, 2

How to do it

Grown-up prep: Find a clear path across a room and set two chairs a few big steps apart, away from doorways and walkways, since the string can be a tripping hazard. Check that nobody has a latex allergy, or use latex-free balloons. You'll be the official balloon handler: you blow up, hold and swap the balloons, and pick up and throw away any popped pieces right away, because they're a choking hazard. Keep spare balloons out of reach.

1. Thread the string through the straw so the straw slides along it.
2. Tie each end of the string to a chair. Pull it tight. Ask for help if you need it
3. A grown-up blows up the balloon and pinches the neck closed, with no knot. A grown-up does this
4. Tape the balloon to the straw, opening facing the nearest chair.
5. Count down 5, 4, 3, 2, 1, then let go and watch it fly!
   Ask: Where did the air go, and which way did the balloon move?
6. Mark where the rocket stopped with a piece of tape.
7. Change one thing and fly it again: balloon size, string length, or slope.
   Ask: Which change made your rocket go fastest or farthest? Why do you think so?
8. A grown-up unties the string and collects every balloon piece. A grown-up does this
9. Now show your friends, or build more! Whose rocket will zoom farthest?
   Ask: What would you change to make the next rocket even faster?

Play it again

• Rocket race: set up two strings side by side and see which rocket zooms first.
• Target landing: put a tape mark on the string and try to stop your rocket right on it.
• Mystery slope: raise one chair a little at a time and guess how far the rocket will go each time.