Try to convert a nail into an artificial magnet by the touch-stroke method.
Take two identical iron pins and magnetize them by the touch and stroke method. Make sure that you are stroking both the pins with equal number of strokes so that they have the same strength as magnets. Now, take a small piece of thermocol and insert both the pins, as shown in the given figure. Place this piece in a small tub filled with water so that it can float. Gently rotate the piece in a particular direction and then observe its motion. Can you guess when this piece of thermocol will stop rotating?
The nail, being magnetic, will behave as a compass and try to align itself with the earth's magnetic field. So, the thermocol will come to rest in such a position that the nail is pointing in the North -South direction.