5-LS2-1: How Matter Cycles Through an Ecosystem
Also called NGSS 5-LS2-1 · Topic: Matter and Energy in Organisms and Ecosystems · Life Science
The Official Wording
Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.
Clarification statement: Emphasis is on the idea that matter that is not food (air, water, decomposed materials in soil) is changed by plants into matter that is food. Examples of systems could include organisms, ecosystems, and the Earth.
Assessment boundary: Assessment does not include molecular explanations.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 5-LS2-1 Means in Plain English
Fifth graders build a model, often a diagram with arrows, that shows matter moving in a loop. Plants turn air and water into food, animals eat plants and each other, and decomposers break down dead things and wastes, returning materials to the soil and air.
The model stays at the level of organisms and materials, with no molecules or chemical formulas. It ties together 5-LS1-1 and 5-PS3-1 and leads to MS-LS2-3, where students model matter cycling and energy flow through whole ecosystems.
5-LS2-1 I Can Statements
- I can draw a model showing matter moving among living things.
- I can explain what decomposers do with dead plants and animals.
- I can show how matter returns to the soil and air.
5-LS2-1 Worked Example
A decomposition bottle the class watches for four weeks, then turns into a matter-cycle model.
What happens to a banana peel and dead leaves left in damp soil?
Set It Up: A clear two-liter bottle with the top cut off, garden soil, dead leaves, a banana peel, an apple core, and a cup of water.
- Layer soil, leaves, and food scraps in the bottle, dampen it, and cover it loosely.Layers sketched on day 1
- Check each week and sketch what changed.Week 1: peel browning, fuzzy mold
- Keep watching and note the size of the scraps.Week 3: apple core shrunken and soft
- Look closely at the leaf layer with a hand lens.Week 4: leaves crumbling, soil darker
- Draw arrows connecting plants, animals, decomposers, soil, and air.A loop with no dead end
The scraps and leaves shrank and broke apart as mold and other decomposers fed on them, leaving darker soil behind.
Why it works: Decomposers break dead matter into simpler materials that go back to the soil and air, where plants can use them again.
Common Mistakes with 5-LS2-1
Leaving decomposers out
A food chain that ends at the top predator
Try this: Every plant and animal dies eventually. Add decomposers with arrows from all of them, and an arrow from decomposers back to soil.
Thinking dead things just disappear
“The apple core is gone, it vanished.”
Try this: Nothing vanishes. Decomposers ate it and turned it into soil materials, gases, and their own bodies, so the matter is still around.
Leaving air out of the model
Arrows only between soil, plants, and animals
Try this: Plants take in carbon dioxide from the air, and animals and decomposers release it. Draw air as its own box with arrows.
Where 5-LS2-1 Fits
Practice 5-LS2-1
Quick Check
- What job do decomposers do in an ecosystem?
- Where does a plant get the matter it needs to grow?
- If all the decomposers vanished, what would happen to fallen leaves?