Instructions
Lay a clock on a flat surface outside during daylight hours, when there is enough sunlight to cast a shadow. If you're wearing a wristwatch, hold it parallel to the ground. If you have a digital watch, draw an analog watch face on the ground or on a piece of paper and mark the hour hand.
Place a match in the center of the clock vertically. Only the tip of the match should be touching the clock, with the rest of the match sticking straight up. A small twig or any other object with a shape similar to a match will work in the same way.
Turn the clock until the shadow from the sun lines up with the clock's hour hand.
Draw an arrow halfway between the hour hand and the 12 o'clock point on the clock. The arrow points toward north. Extend the arrow in the opposite direction to point south. Your clock now acts as a compass.