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Thinking play

Shadow Length Experiment

Child measures how the LENGTH of their shadow changes between morning and afternoon and reasons about why, going beyond just marking its position.

Cartoon illustration of a parent and child outdoors doing Shadow Length Experiment.
  • Age6 to 10 years
  • Time15 to 30 minutes
  • EnergyModerate
  • CostFree
  • WhereOutdoors
  • PrepNone

Your child measures how long their shadow is in the morning and again later in the day, then talks through what they notice about the change.

How to do it

  1. In the morning, find a sunny spot where your child can stand and cast a clear shadow, and mark where their feet are so they can stand in the same place later.
  2. Measure the length of the shadow together using steps, a piece of string, or a tape, and write down how long it was.
  3. Come back to the same spot in the afternoon with your child standing in the same place, and measure the shadow again.
  4. Compare the two lengths and ask your child what they notice and why they think it changed.
  5. If they are curious, add a third measurement near the middle of the day to see the shadow at its shortest.

What you need

  • Sunny spot
  • String
  • Paper
  • Chalk

Make it yours

Younger, 5-6 years: Just compare longer versus shorter by laying the two strings side by side, no numbers. Older, 8-10 years: Record several times across the day and look for the pattern of when the shadow is longest and shortest. Siblings: Each child measures their own shadow and compares whether they all changed the same way

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