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A balloon being blown up with tiny dots drawn inside to show air particles.

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Matter Is Made of Particles

Air in a balloon shows it.

Lesson 13 of 41

Try this first

Before we start

Today’s story

Matter Is Made of Particles

A balloon is stretched tight, yet it looks empty. Air is invisible. Still, it has mass and takes up space.

Matter is made of particles too small to see, even with a hand lens. In a gas, the particles are far apart and moving fast. They bump into the walls of the balloon and push outward.

We cannot see particles, so we use clues. Let us look at some.

See it

Five steps. Every time.

    Hands on

    Dry Paper Towel Dive

    20 minutes · Do this with a grown-up nearby

    You need

    • a clear plastic cup
    • a paper towel
    • a tub or sink of water
    • a small balloon
    • a pencil
    • paper

    Do this

    1. Predict whether a paper towel inside a cup will get wet when the cup goes under water.
    2. Crumple the paper towel and wedge it in the bottom of the cup.
    3. Turn the cup upside down and push it straight down into the water.
    4. Lift it straight up and check the paper towel.
    5. Tip the cup sideways under water and watch what rises.
    6. Draw particles of air inside the cup.
    Write or draw: A drawing of the cup before, during and after, with dots for air particles, and a note on whether the towel stayed dry.

    Watch for: The towel stays dry because air takes up the space. Bubbles rise when the cup tips and air escapes.

    Safety: Wipe up spills right away so no one slips. Do not put balloons in your mouth.

    Same every time

    Three rules

    Rule 1Use clues for the unseen

    Evidence can show things we cannot see.

    Rule 2Draw models carefully

    Dots stand for particles.

    Rule 3Remember gas has mass

    Air is not nothing.

    Grandpa Fenn’s notebook

    Say it like a scientist

    particle
    A piece of matter too small to see.
    gas
    Matter with no fixed shape or volume.
    matter
    Anything with mass that takes up space.
    model
    A picture or build that helps us understand.

    Poppy’s quiz

    Six questions

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

    Talk about it

    Say it out loud

    • What evidence shows air takes up space?
    • Where do you feel moving air at home, like a fan or a tire pump?
    Did you know

    Air feels like nothing, yet the air in a classroom has a mass of well over a hundred kilograms.

    Someone who does this

    A tire technician checks air pressure so tires carry loads safely.

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