Shadow stick sun clock

Push a stick into open ground, mark the tip of its shadow every hour, and watch the sun tell the time.

How it goes

1. Pick a sunny, open spot and push a straight stick upright into the ground.
2. Mark the end of its shadow with a stone and note the time.
3. Come back every half hour or hour and add a new stone.
4. Look at the line the stones make. Which way is north?
5. Best of all on the longest day of the year.