Science Fenns K-5Grades K to 5
A girl holding a small clay model of a volcano beside a photo of a real mountain, on a craft table.

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Models and Their Limits

A model helps you see. A model also leaves things out.

Lesson 5 of 41

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Today’s story

Models and Their Limits

Ana builds a clay volcano for class. It has a cone and a hole in the top. It is brown and red. It looks like a picture she saw.

The clay volcano is a model. It helps her see the shape. It does not erupt like a real one. It is much smaller. It does not get hot.

Models help us learn about things that are too big, too small or too far away. They also leave things out. The steps show how to use one well.

See it

Five steps. Every time.

    Hands on

    Build a model of your hand

    20 minutes · Do this with a grown-up nearby

    You need

    • Paper
    • Pencil
    • Craft sticks
    • String
    • Tape
    • Scissors with adult help

    Do this

    1. Trace your hand on paper.
    2. Tape craft sticks on as finger bones.
    3. Join them with string at the joints.
    4. Pull a string to bend a finger.
    5. Compare it with your real hand.
    6. Write what the model shows.
    7. Write what it leaves out.
    Write or draw: Two lists. What it shows. What it leaves out.

    Watch for: Notice that the model bends like a finger, but it has no skin or muscles.

    Safety: Ask an adult to cut the sticks or string. Keep scissors closed when you walk.

    Same every time

    Three rules

    Rule 1Say what the model shows.

    That is how you use it to learn.

    Rule 2Say what it leaves out.

    Every model has limits.

    Rule 3Improve it if you can.

    A better model can show more.

    Grandpa Fenn’s notebook

    Say it like a scientist

    model
    A picture or object that stands for something real.
    limit
    What a model cannot show or do.
    scale
    How much smaller or bigger a model is than the real thing.

    Poppy’s quiz

    Six questions

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

    Talk about it

    Say it out loud

    • What does your model show? What does it leave out? How do you know?
    • What models do you see at home, like a toy tractor, a map or a plan?
    Did you know

    Engineers test small models of bridges and airplanes before they build the real thing.

    Someone who does this

    An engineer builds models to test ideas before making something full size.

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