Science Fenns K-5Grades K to 5
A child kneeling on a driveway tracing the chalk outline of a tall stick's long morning shadow.

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Shadow Changes

Track a shadow through the day.

Lesson 25 of 41

Try this first

Before we start

Today’s story

Shadow Changes

Hold a stick in the sun and you get a shadow. It lies on the ground away from the Sun. Early in the morning that shadow is long. It points west.

As the Sun climbs, the shadow gets shorter. At midday it is the shortest of all. Later the shadow stretches again, and now it points east.

This happens because the Sun's position changes, as Earth spins. A low Sun makes a long shadow. A high Sun makes a short one. The steps show how to read it.

See it

Five steps. Every time.

    Hands on

    Shadow Stick

    15 minutes, three times in a day · Do this with a grown-up nearby

    You need

    • a stick or ruler
    • clay or a cup of dirt to hold it up
    • chalk
    • a ruler or tape measure
    • paper and pencil

    Do this

    1. Press the stick upright in clay on a sunny sidewalk.
    2. Predict how the shadow will change by noon.
    3. Trace the shadow with chalk and write the time.
    4. Measure the shadow length and write it down.
    5. Come back at two other times and do it again.
    6. Compare the three lengths.
    Write or draw: A table with time, shadow length and which way the shadow points.

    Watch for: The shortest shadow is near noon. The shadow swings from west to east through the day.

    Safety: Stay on a safe sidewalk, away from cars, and do not look at the Sun.

    Same every time

    Three rules

    Rule 1Measure from the same spot.

    Move the object and your data is wrong.

    Rule 2Shadows point away from the Sun.

    Find the Sun and you can predict the shadow.

    Rule 3Record the time with each measurement.

    Time is the story behind the length.

    Grandpa Fenn’s notebook

    Say it like a scientist

    shadow
    A dark shape made when an object blocks light.
    length
    How long something is from one end to the other.
    prediction
    A careful guess about what will happen.
    noon
    The middle of the day, when the Sun is highest.

    Poppy’s quiz

    Six questions

    Tap an answer. Green means right. You will see why.

    Talk about it

    Say it out loud

    • What evidence do you have that the Sun's position makes the shadow change? Could anything else do it?
    • Where is the coolest, shadiest spot at your school at 3 o'clock? How do you know?
    Did you know

    A shadow stick, called a gnomon, was one of the first clocks. The Egyptians used shadows to tell the time.

    Someone who does this

    An architect plans buildings and thinks about where shadows will fall on the ground.

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