What you need: sheet of paper, scissors, pencil, thread, and a heat source such as a light bulb
What you do:
- Draw a big circle on the paper. Then draw a spiral inside - it should go about one and a half times around the circle - and then cut it out.
- Tie or staple the thread in the center of the spiral. For this experiment, it’s important to use light-weight thread like you’d use for sewing, not kitchen twine or ribbon. This is because the thread allows the spiral to spin freely. If you’re tying the thread, it works well to poke a tiny hole in the paper with a pencil or an earring, and then anchor it with a big knot.
- Tie the other end of the thread to the pencil, and pick up the spiral - it should uncoil like a paper snake. Let it hang freely and wait until the thread untwists and the spiral is still. With help from a grown-up assistant, move the spiral over a heat source such as a hot light bulb pointed up at the ceiling. Center the spiral right over the light bulb, and watch your spiral spin!
Why it works (or Other Variations to try)
In this experiment, the light bulb is warming the air around it. Warm air is less dense than the colder air around it, so the cold air can push the warm air up, creating wind that spins our spiral!