Science Fenns K-5Grades K to 5
Four clear glasses of water with salt, sand, sugar and pepper each stirred in, showing which vanish and which stay.

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Dissolve or Not

Solubility in water.

Lesson 10 of 41

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Before we start

Today’s story

Dissolve or Not

Stir a spoon of sugar into iced tea. It seems to disappear. Stir in sand and it stays swirling and then sinks.

Solubility is how well a material dissolves in a liquid. Sugar is soluble in water. Sand is insoluble in water.

Many things affect how fast something dissolves, like stirring and temperature. Let us test.

See it

Five steps. Every time.

    Hands on

    Dissolve Test

    25 minutes · Do this with a grown-up nearby

    You need

    • Four clear cups
    • Room-temperature water
    • Salt
    • Sugar
    • Sand
    • Pepper
    • Teaspoon
    • Tablespoon for stirring

    Do this

    1. Predict which will dissolve.
    2. Pour equal water into four cups.
    3. Add one teaspoon of each to its own cup.
    4. Stir for 30 seconds.
    5. Let the cups sit for two minutes.
    6. Record what you see in each.
    Write or draw: A table with substance, prediction, result and a sketch.

    Watch for: Is the water clear, cloudy or full of bits? Is anything on the bottom?

    Safety: Do not taste any of it. Use kitchen items only.

    Same every time

    Three rules

    Rule 1Use the same amount of water

    This keeps it fair.

    Rule 2Look closely

    Check the bottom and the top.

    Rule 3Give it time

    Some things dissolve slowly.

    Grandpa Fenn’s notebook

    Say it like a scientist

    soluble
    Able to dissolve in a liquid.
    insoluble
    Not able to dissolve in a liquid.
    solution
    A mix where one thing is evenly spread in another.
    solubility
    How well something dissolves.

    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 solid dissolved?
    • What dissolves in your kitchen, like sweet tea or cocoa?
    Did you know

    Seawater holds so much dissolved salt that you cannot see it, yet you can taste it.

    Someone who does this

    A chemist tests how well new medicines dissolve.

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