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Outdoor Shadows

Science Snack
Outdoor Shadows
Trace your shadow, then watch it change.
Outdoor Shadows
Trace your shadow, then watch it change.

Go outside and trace an outline of your shadow. Wait a while, try again, and watch how your shadow changes over time.

Tools and Materials
  • Chalk
  • A partner
  • A sunny day
  • A chalk-safe surface

None needed.

To Do and Notice

Caution: Do not look directly at the sun.

Choose a safe outdoor space in a sunny area. The area should include a hard surface, such as a driveway or sidewalk, where you can make chalk outlines. 

Have your partner stand still, in whatever pose they choose, while you use chalk to outline their shadow. Be sure to also outline the shadow-maker’s feet to show where they were standing. Now go to a different spot and switch roles, so you become the shadow-maker. Have your partner draw around your shadow and outline your feet.

Come back after about 15 minutes and place your feet in the chalk outlines, exactly where they were before. Look carefully at your shadows. Have they changed position? Are they longer or shorter? Why do you think they’re different now? Trace the new outlines of your shadows.

What’s Going On?

In order to create a shadow, you need three things: light, something blocking the light, and a surface for the shadow to fall on. A shadow is an area where light is being blocked. You see your shadow outside because light from the sun is being blocked by your body. Light travels in straight lines, so it cannot bend around your body to light up the blocked parts of the surface.

Outdoor shadows change because the earth is always moving. It happens naturally every sunny day or moonlit night. When you’re outside on a sunny day, your shadow always falls on the opposite side from where the sun is. As the sun changes position in the sky, your shadow changes position as well. 

Going Further

There are lots of fun things you can do to find out more about shadows. 

Try making your shadow as small as you can, and then as big as you can. Can you change the shape of your shadow? Try making it go up steps or around a corner.

Stand with your shadow in front of you. Can you touch your shadow head with your real hand, or step on your shadow head with your real foot? Try shaking shadow hands with the person next to you without touching your real hands. 

Try doing shadow outlines early or late in the day to create huge, distorted shadows. Or try tracing shadow silhouettes of other objects, like bicycles or playground structures. 

If you trace the same object at regular intervals (every 20 minutes, for instance) using a different color each time, you can create a beautiful piece of art! 

Teaching Tips

Encourage learners to engage in science practices by having them raise questions about their shadows. Then help them plan and carry out investigations to answer those questions. You might also try making predictions. Predict where your shadow will be in 30 minutes, and draw it in a different color. How did you do? The more outlines you make, the more data you will have. Try outlining your shadow every few hours. What does your data tell you?