Science Fenns K-5Grades K to 5
Two creek scenes side by side, one clear with plants and fish, the other muddy with litter and few animals.

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A Healthy Ecosystem

Signs of health and signs of trouble.

Lesson 37 of 41

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Before we start

Today’s story

A Healthy Ecosystem

A healthy ecosystem has many kinds of living things. It has clean water, good soil and enough food. Each part has a job. Plants make food and animals spread seeds. Decomposers recycle.

Many kinds of life make an ecosystem strong. If one kind is hurt, others fill in. A creek with many insects, fish, birds and plants is usually healthy. A creek with only a few kinds may be in trouble.

Signs of trouble include dead fish, murky water, bare banks and lots of litter. Scientists measure these signs to check on a place. Here are the steps.

See it

Five steps. Every time.

    Hands on

    Schoolyard Survey

    30 minutes · Do this with a grown-up nearby

    You need

    • a hula hoop or string square
    • a clipboard
    • a hand lens
    • a notebook
    • a small jar

    Do this

    1. Lay the hoop on the ground.
    2. Count the kinds of plants inside.
    3. Count the animals or signs of animals, like insects or holes.
    4. Note the soil, wet or dry.
    5. Look for litter.
    6. Repeat in a second spot.
    Write or draw: A table comparing the two spots by number of kinds of plants, animals, soil and litter.

    Watch for: The spot with more kinds of plants often has more insects. Bare, trampled ground has fewer.

    Safety: Stay on safe ground. Do not touch anything that stings or bites. Wash your hands.

    Same every time

    Three rules

    Rule 1Variety shows health.

    Many kinds of life makes a place strong.

    Rule 2Look for evidence.

    Count species, test water, note the soil.

    Rule 3Trouble can be fixed sometimes.

    Cleaning up and replanting can help.

    Grandpa Fenn’s notebook

    Say it like a scientist

    biodiversity
    The variety of living things in a place.
    pollution
    Harmful material added to air, water or soil.
    balance
    When no one group takes over and needs are met.
    indicator
    A sign that tells you about the health of a place.

    Poppy’s quiz

    Six questions

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

    Talk about it

    Say it out loud

    • What evidence would convince you an ecosystem is healthy?
    • What does the nearest creek or pond look like? Is it healthy?
    Did you know

    Some tiny insects, like mayfly nymphs, need clean, oxygen-rich water, so finding them is a good sign.

    Someone who does this

    A water quality scientist tests streams and lakes for health.

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