Science Fenns K-5Grades K to 5
A girl reading a thermometer in a cup of water beside a kitchen scale holding an apple, on a sunny counter.

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How Warm? How Heavy?

Measure temperature and mass and write the numbers down.

Lesson 8 of 41

Try this first

Before we start

Today’s story

How Warm? How Heavy?

Kai picks up two apples. They look the same. One feels heavier. He wants a number, not a feeling.

He puts each on a scale. The numbers say 150 grams and 180 grams. Now he knows. He does the same with a thermometer for the water.

Temperature and mass are things you can measure and write down. The steps show how to do it well.

See it

Five steps. Every time.

    Hands on

    Warm, cool, heavy

    20 minutes · Do this with a grown-up nearby

    You need

    • Celsius thermometer
    • Digital scale
    • Three cups
    • Cold tap water
    • Room-temperature water
    • Warm tap water
    • A few small objects

    Do this

    1. Set the cups in a row with a different water in each.
    2. Predict which is coldest and warmest.
    3. Put the thermometer in the first cup and wait one minute.
    4. Read and write the number.
    5. Repeat for the other two cups.
    6. Weigh three small objects on the scale.
    7. Write each mass in grams.
    Write or draw: A table with each cup's temperature and each object's mass.

    Watch for: Notice whether your predictions matched the numbers.

    Safety: Use warm water from the tap only, never hot. Keep scales and water apart.

    Same every time

    Three rules

    Rule 1Wait for the numbers to settle.

    A moving reading is not final.

    Rule 2Always write the unit.

    12 what? 12 degrees. 12 grams.

    Rule 3Measure twice.

    Two readings catch mistakes.

    Grandpa Fenn’s notebook

    Say it like a scientist

    temperature
    How warm or cold something is.
    mass
    How much matter an object has.
    degrees Celsius
    The unit for temperature in science.

    Poppy’s quiz

    Six questions

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

    Talk about it

    Say it out loud

    • What did you measure? How do you know your numbers are right?
    • What do you measure at home, like a pot of water or a bag of rice?
    Did you know

    A cup of water has more mass than a cup of air of the same size.

    Someone who does this

    A cook measures temperature and mass to bake safely and well.

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