Science Fenns K-5Grades K to 5
A boy on a porch steps comparing a leaf under a hand lens, with a ruler, thermometer, scale and timer laid out on a wooden board.

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Tools in Your Hand

Hand lens, ruler, thermometer, scale and timer. Pick the right one.

Lesson 2 of 41

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Before we start

Today’s story

Tools in Your Hand

Marisol finds a pecan on the ground. She wants to know how long it is. She holds it up and guesses. Her friend guesses something else.

Guessing gets two answers. A ruler gets one. Tools give everyone the same number to look at.

A scientist picks the tool that fits the question. The steps show you five tools and what each one tells you.

See it

Five steps. Every time.

    Hands on

    Measure five things

    25 minutes · Do this with a grown-up nearby

    You need

    • Hand lens
    • Metric ruler
    • Digital scale
    • Celsius thermometer
    • Timer
    • Cup of tap water
    • A pencil, a leaf and a coin

    Do this

    1. Choose three small objects.
    2. Look at each one with the hand lens and draw one close detail.
    3. Measure the length of each with the ruler.
    4. Find the mass of each on the scale.
    5. Put the thermometer in the cup of water and wait one minute.
    6. Read it and write it down.
    7. Time how long it takes you to measure the leaf again.
    Write or draw: A table with the object, length in cm, mass in g and one detail.

    Watch for: Compare your numbers with a partner. If they differ, find out why.

    Safety: Never use a glass thermometer without an adult. Do not put a thermometer in hot water.

    Same every time

    Three rules

    Rule 1Pick the tool for the question.

    A ruler cannot tell you how warm something is.

    Rule 2Read it carefully and write it down.

    Write the number and the unit, like 12 cm.

    Rule 3Measure more than once.

    A second try can catch a mistake.

    Grandpa Fenn’s notebook

    Say it like a scientist

    hand lens
    A glass that makes small things look bigger.
    mass
    The amount of stuff in an object. We measure it in grams.
    thermometer
    A tool that measures how warm or cold something is.

    Poppy’s quiz

    Six questions

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

    Talk about it

    Say it out loud

    • Which tool would you use to measure a leaf? How do you know?
    • What do you measure at home, like cooking or growing?
    Did you know

    The metric system is used by scientists all over the world. That way a centimeter means the same thing everywhere.

    Someone who does this

    A nurse uses a thermometer and a scale many times a day to care for patients.

    BeforeSafe ScientistsNext lessonAsk a Question, Then Look