Build a balloon-powered car with Rocky

What you will need:

• A plastic bottle
• Four plastic bottle caps or four cotton reels
• Wooden skewers
• Two straws
• A balloon
• Sticky tape
• Scissors or a sharp knife (you will need an adult to help you)
• A grown-up helper

What to do:

1. Cut one of the straws in half.
2. Use sticky tape to secure both pieces of the straw separately to one side of the water bottle.
3. With the help of an adult, cut the wooden skewer in half and push each piece through one of the straws. These will form your axles.
4. Ask an adult to use the scissors to poke a ‘+’ shaped hole directly in the centre of each plastic bottle cap.
5. Press each bottle cap onto the ends of the wooden skewers. These will form your wheels.
6. Put your car down on a flat surface and give it a good push. Make sure the car rolls easily for a bit before stopping. If your car gets stuck or does not roll smoothly make sure your axles are parallel to each other, the hole in each bottle cap is centered, and the straws are securely taped to the water bottle and do not wobble.
7. Use sticky tape to secure the neck of the balloon around one end of the other straw. Wrap the tape very tightly so the connection is airtight.
8. With an adult helping you, cut a small hole in the top of the water bottle. The hole should be just big enough to push the straw through.
9. Push the free end of the straw through the hole and out the mouth of the bottle.
10. Use sticky tape to secure the straw to the bottle.
11. Blow through the straw to inflate the balloon, then put your finger over the tip of the straw to trap the air.
12. Put the car down on a flat surface, release your finger and watch the car go!