How to Make a Working Compass with Your Kids

Learn to create a simple working compass using basic household materials in this fun STEM activity for families.

1. Gather Your Materials. You'll need a sewing needle, a small magnet (like a refrigerator magnet), a small piece of cork or foam, a shallow bowl, water, and a compass app or real compass to test your results. The needle should be made of steel - most sewing needles work perfectly. If you don't have cork, a small piece of styrofoam or even a bottle cap can work as a float.
2. Magnetize the Needle. Hold the needle by its eye and stroke it with the magnet from the eye to the point about 50 times, always moving in the same direction. Don't stroke back and forth - only go one way, then lift the magnet and start again from the eye. This process aligns the metal particles in the needle, turning it into a magnet itself. The more times you stroke it, the stronger your compass will be.
3. Prepare the Float. Cut a small piece of cork about the size of a coin, or use a small piece of foam. The float needs to be just big enough to support the needle without sinking. Carefully push the magnetized needle through the center of the cork so it lies flat across the surface. Make sure the needle is balanced and the cork can float freely.
4. Test Your Compass. Fill your bowl with water and gently place the cork and needle on the surface. The needle should start to turn and eventually point toward magnetic north. It might take a minute or two to settle. Compare your homemade compass with a real compass or compass app to see how accurate it is. The needle will align with Earth's magnetic field, just like a store-bought compass.
5. Experiment and Learn. Try moving a magnet near your compass to see how it affects the needle. Test your compass in different rooms of your house. Talk with your kids about why the needle points north and how sailors and explorers used compasses to navigate. You can also try making multiple compasses to see if they all point the same direction.