What are the ways you can navigate when you don't have a compass or a GPS? For example how can you tell which way is north.
If you look at the current time, and imagine yourself in the center a big analog watch, just place your shadow on the location of the hour's hand. Then imagine the location of the 12 o'clock hand, and exactly in the middle of the angle between those two hands is the north.
Be sure to ignore daylight saving time (As the time your hand watch is showing during daylight saving is not the "real" astronomical time), and also don't ignore the minutes (so at 15:20 the hand is a 1/3 of a way further on, between 15 and 16).
I also don't know how it works in the southern hemisphere (It might point directly south? I'm not sure - anyone wants to try it out?).
You can also just use a stick to create the shadow for the hour's hand. But using your own shadow makes for a nice trick.