Food webs and matter in ecosystems (grade 5) · lesson

Producers and consumers

💡 Producers make their own food from sunlight, and consumers get food by eating other living things.

Plants are producers. They use sunlight to make their own food. An oak tree is a producer.

Animals are consumers. They eat to get food. A rabbit eats plants. A fox eats other animals.

Mushrooms are not producers. They are decomposers that feed on dead things.

🧠 How to think about it

Ask: does it make its own food from sunlight? Yes means producer. If it eats something else, it is a consumer.

💡 Living things in an ecosystem are linked by what they eat, so a change to one affects the others.

A food chain shows who eats whom. It starts with a plant. Grass, then grasshopper, then frog, then snake.

Many food chains cross over each other. Together they make a food web.

If one living thing disappears, others change. If insects that eat algae die, the algae grows more. The fish that eat insects go hungry.

Living things also trade gases. Plants give off oxygen. Animals give off carbon dioxide, which plants use.

🧠 Let's work it out

What do you think comes next?

💡 Decomposers break down dead things and return matter to the soil so plants can use it again.

Decomposers feed on dead plants and animals. Fungi like mold and mushrooms are decomposers. So are many bacteria.

They break dead things into tiny bits. Those bits become nutrients in the soil.

Plant roots take in the nutrients. So matter goes around in a cycle: leaf, decomposer, soil, roots, new leaf.

Without decomposers, dead leaves and logs would pile up. The soil would run low on nutrients.

🧠 Let's work it out

What do you think comes next?

💡 Plants build their bodies mostly from carbon dioxide in the air and from water, using energy from the sun.

A plant gets much heavier as it grows. But the soil in its pot hardly loses any weight. So where does the new matter come from?

Plants take in carbon dioxide, a gas in the air, through their leaves. They take in water through their roots.

Using sunlight for energy, they turn carbon dioxide and water into food and plant matter. Sunlight gives the energy, not the matter.

🧠 Let's work it out

What do you think comes next?

carbon dioxide: a gas in the air that animals breathe out and plants take in