Science Fenns K-5Grades K to 5
A table with a marble, a block of wood, a steel nut, a bowl of water, a magnet and a balloon, laid out for sorting.

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Compare Matter

Mass, volume, density, state and magnetism.

Lesson 8 of 41

Try this first

Before we start

Today’s story

Compare Matter

Look at a rock, a cup of water and the air in a balloon. All are matter. Matter is anything that has mass and takes up space.

Mass tells how much matter there is. Volume tells how much space it takes. Density tells how tightly the matter is packed. State tells whether it is a solid, a liquid or a gas. Some matter is drawn to a magnet and some is not.

A scientist can sort almost anything with those few ideas. Let us see how.

See it

Five steps. Every time.

    Hands on

    Mystery Object Sort

    30 minutes · Do this with a grown-up nearby

    You need

    • Kitchen scale or balance
    • Magnet
    • Tub of water
    • Five small objects such as a cork, nail, coin, rubber band and eraser
    • Paper and pencil

    Do this

    1. Predict whether each object will sink and whether the magnet will pull it.
    2. Find the mass of each object.
    3. Test each in water and record sink or float.
    4. Hold the magnet near each one.
    5. Make a chart with all four properties.
    6. Compare your predictions to your results.
    Write or draw: A chart with object, mass, sink or float, and magnetic or not.

    Watch for: Did the heaviest object always sink? Did the biggest?

    Safety: Dry up spills right away so no one slips.

    Same every time

    Three rules

    Rule 1Compare with measurements

    Words like heavy are weak. Grams and milliliters are strong.

    Rule 2Test, do not guess

    Drop it in water. Hold the magnet near.

    Rule 3Use the same tools each time

    This keeps the comparison fair.

    Grandpa Fenn’s notebook

    Say it like a scientist

    mass
    The amount of matter in an object.
    volume
    The amount of space something takes up.
    density
    How much mass is packed into a space.
    magnetic
    Pulled by a magnet.

    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 which object is denser?
    • What floats and what sinks in a stock tank or a pond near you?
    Did you know

    A ship made of steel floats because its hollow shape makes the whole ship less dense than water.

    Someone who does this

    A materials engineer picks the right matter for a bridge, a phone or a pot.

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