• A flowerpot or short cup with sloping sides
• A long, thin stick (a few inches taller than your flowerpot)
• A marker

Tape a long stick into the center of the cup, standing on end.

As the day goes by, use a marker to note where on the pot the shadow lands every hour. After the first day, you can use your clock to read off the time whenever the sun is out.

What happened?

Because of the Earth’s rotation, the sun appears to move across the sky each day. Depending what time of day it is, the shadows produced by objects blocking the light of the sun fall in a certain direction. These will be in about the same place every day. (Your clock may need readjustment as the seasons change.)