How do you find the direction to north if you don’t have a magnetic compass or a fancy GPS? One way is to find the North Star, Polaris—it’s always directly north. But during the day, when you can’t see Polaris, what do you do?

Well, you can do the same thing people in different parts of the world have been doing for thousands of years: stick a stick in the ground and watch its shadow.

This will take a little time (at least two hours), and has to be done outside in the middle part of the day—so turning this activity into a nice picnic is a great idea! (I’ll leave the food details to you.)

What to do:

1. Find a nice flat area outside in the sunlight and push the stick into the ground so that it points straight upward (make it vertical).

2. Late in the morning (11am or earlier), start marking where the tip of the stick’s shadow falls on the ground. You can use sidewalk chalk if the shadow falls on a hard surface or you can place small rocks at the tip’s shadow if you can’t write on the ground.

3. Keep marking the shadow’s tip every 15 minutes or so, as the shadow slowly moves. (Why is it moving? What direction is it moving? Keep in mind: the shadow always points away from the sun.)

4. You will begin to see a shape in the markings you have made: a long curve.
If you made enough marks, you should eventually see a nice, wide curve on the ground. You should also see that the earlier or later in the day you made the marks, the longer the distance from the stick to the curve (in other words, the longer the shad­ow), with the shortest distance somewhere in the middle.

5. Next draw a circle on the ground around the base of the stick, large enough so it crosses your marked curve at two points—look at the draw­ing above to see what I mean. Use a stretched piece of string tied to the stick to guide your drawing hand and make the circle perfect.

6. Draw a straight line between those two points where the circle crosses your curve.

7. Using a tape measure, find the exact middle of the straight line—the spot halfway between the points where it meets your curve.

8. Finally, draw a straight line from that midpoint mark and the stick.

The line you just drew points north and south; the end of the line at the stick points south, the other end points north.

What’s happening?

As the sun moves through the sky each morning it rises higher and higher in the sky—and shadows that it casts get shorter and shorter. Then, in the afternoon, the sun gets lower and lower and shadows grow longer and longer.

At noon the sun is highest in the sky, and is directly south for us in the Northern Hemisphere. At this time, shadows are at their shortest and point directly north.

So if you find the time of day when the shadow of your stick is shortest, you know the shadow is pointing north and you know what direction to go!