Hold a needle carefully. Run a magnet along the length of the needle to magnetize the metal and make it sensitive to the magnetic field of the earth.
Place a wine bottle cork on a work surface. Turn the cork on its side and cut a 1/2 inch thick disc from the cork with a sharp knife.
Insert the needle through the cork from one edge to the other.
Add water to a cup or container. Place the cork with inserted needle in the container so it floats on the water surface.
Leave the container and contents to settle. Monitor the needle as it begins to settle and watch as it points toward magnetic north.