You’ll need

  • An old CD
  • A pop-top lid from a drink bottle
  • Craft glue
  • A balloon

What to do

  1. Gather your materials on a flat surface.
  2. Close the pop-top lid.
  3. Place some glue around the hole of the CD and glue the lid pop-top up over the hole.
  4. Let the glue dry. This could take 20 to 30 minutes. Be patient!
  5. Blow up a balloon and pinch the neck so that no air can escape.
  6. Stretch the neck of the balloon over the pop-top.
  7. Let your hovercraft go and push it. How far does it move?
  8. Open the pop-top lid and push the hovercraft. How far does it move this time?

Questions to ask

Try changing the design of the hovercraft by using different materials. For example, use an old vinyl record as the base or use different-sized balloons. Which ones work best?

Use your hovercraft on different surfaces, like carpet or grass. What surfaces are best to hover on?

What's happening

When the pop-top lid is opened, air flows out of the balloon, down through the pop-top and under the CD.

The CD is weighted evenly across the whole surface. The surface is also very flat. So the air lifts the entire CD off the surface of the table. The layer of air between the tabletop and the CD reduces the friction between the 2 surfaces, so the CD hovercraft can glide easily across the table.

Did you know

An air hockey table works using the same principles as your CD hovercraft. A fan under the hockey table pushes air through tiny holes on the table’s surface. The flowing air decreases the friction between the hockey puck and the table, allowing the puck to move quickly and freely. Score!