Science Fenns K-5Grades K to 5
A cracked Texas boulder with a small plant growing out of a crack and pieces of rock at its base.

Science / All lessons / Water, Weather and Slow Change

Weathering

How rock breaks into pieces.

Lesson 26 of 40

Try this first

Before we start

Today’s story

Weathering

Look at an old rock by a creek. The surface is rough. There may be cracks and crumbs. Rock does not stay whole forever.

Weathering is the breaking down of rock into smaller pieces. It happens in place. A tree root pushes into a crack. Water freezes and expands. Rain slowly dissolves some rocks, like limestone.

Weathering is slow. Sometimes it takes thousands of years. But it never stops. Follow the steps.

See it

Five steps. Every time.

    Hands on

    Shake the Rocks

    20 minutes · Do this with a grown-up nearby

    You need

    • Sugar cubes
    • Hard candy or small stones
    • Two jars with lids
    • Paper towels
    • Magnifying glass

    Do this

    1. Look closely at the sugar cubes and the stones with the hand lens.
    2. Put 3 sugar cubes in one jar and 3 small stones in another.
    3. Close the lids tight.
    4. Shake each jar for two minutes.
    5. Open and look at what is inside.
    6. Sketch each result.
    7. Say which broke apart faster.
    Write or draw: Two drawings and a sentence comparing which broke down faster.

    Watch for: Sugar crumbles quickly. The stones barely change. Real rock weathers like the stones, only slower.

    Safety: Wipe up spills and do not eat the materials.

    Same every time

    Three rules

    Rule 1Weathering breaks rock in place.

    Moving the pieces is a different job.

    Rule 2Small changes add up.

    Slow does not mean small.

    Rule 3Different rocks weather differently.

    Soft rock breaks sooner than hard rock.

    Grandpa Fenn’s notebook

    Say it like a scientist

    weathering
    The breaking down of rock into smaller pieces.
    sediment
    Small bits of rock, sand and soil.
    limestone
    A rock that dissolves slowly in rainwater.
    expand
    To take up more space.

    Poppy’s quiz

    Six questions

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

    Talk about it

    Say it out loud

    • How do you know a rock has been weathered?
    • Where have you seen a cracked rock or sidewalk near home?
    Did you know

    The Grand Canyon is partly the result of long weathering and erosion.

    Someone who does this

    A geologist reads rocks to learn how they changed.

    BeforeThe Water CycleNext lessonErosion and Deposition