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Evening · Science

Build a working compass from a needle and a leaf

Rub a needle on a magnet. Float it on water. North reveals itself.

30 min ages 711· Screen-free

How to do it

Take a sewing needle. Rub it firmly in ONE direction (always the same direction!) across a strong magnet, 30-40 times. Float a small leaf or piece of cork on a bowl of water. Carefully place the needle on top. Watch — within 30 seconds it swivels and points north-south. Confirm with a phone compass. They magnetized the needle. Talk about what it means: every atom in the needle has a tiny magnetic field, and rubbing aligned them all. Earth itself is a magnet. Sailors used to do exactly this trick to navigate. Take the compass outside and walk north.

What you'll need

  • Sewing needles

    Amazon
  • Strong neodymium magnets

    Amazon
  • Small leaf, cork, or paper

    Free
  • Bowl of water

    Free
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