Ecosystem Roles

Overview

In this lesson, students identify and model how matter moves through an ecosystem by focusing on three roles: producers, consumers, and decomposers. Students build on prior unit learning about ecosystems and food webs by using a simple model to show interdependence and matter flow.

Learning intentions

Students will be able to:

• WALT identify producers, consumers, and decomposers in a local ecosystem example.
• WALT explain how organisms depend on each other for food and for the cycling of matter.
• WALT use a model to show how matter (not just energy) moves between plants, animals, decomposers, and the environment.
• WALT describe that matter from air, water, and decomposed materials is changed and reused by living things.

Success criteria

Students can:

• Sort organisms into the correct roles: producers, consumers, or decomposers.
• Correctly label arrows in a class model showing how matter moves from one role to another.
• Give an evidence-based statement connecting decomposers to returning matter to the environment.
• Use academic sentence frames to describe interdependent relationships (e.g., “Plants make food and consumers obtain food from plants/animals”).

Curriculum links

• 5-LS2-1: Develop a model to describe movement of matter among plants, animals, decomposers, and the environment.
• Clarification focus within 5-LS2-1: Matter that is not food (air, water, decomposed materials in soil) is changed by plants into matter that is food.
• Assessment aligns with 5-LS2-1 boundary: no molecular explanations; focus on system-level matter flow.

Lesson structure (45 minutes)

1. 0–5 min · Hook. Teacher displays three quick scenario cards (e.g., “grass growing,” “rabbit eating grass,” “mushrooms on a log”) and asks students to point to which card best fits “makes food,” “eats food,” and “breaks down.” Students respond with quick hand signals and brief partner talk.

2. 5–12 min · Mini-lesson: Roles and interdependence. Teacher uses a simple diagram of an ecosystem patch (plants, animals, decomposers, soil/air/water labels) to define producer, consumer, decomposer, emphasizing “matter moves” and “roles are connected.” Students complete a short role-matching chart: organism → role → what happens to matter.

3. 12–22 min · Model construction (small groups). Teacher distributes one blank “Matter Movement Model” sheet with arrows and role boxes, plus a word bank (air, water, plants, animals, decomposers, soil, decomposed materials, food). Students build a group model for a chosen ecosystem example (forest floor, pond edge, or school garden), using evidence from scenario cards and class definitions.

4. 22–30 min · Gallery walk + teacher conferencing. Teacher posts groups’ models around the room and provides a “Glow and Grow” checklist: one correct arrow connection, one needed fix, and one explanation sentence. Students rotate and leave brief written feedback or sticky-note comments using the checklist.

5. 30–38 min · Whole-class sensemaking (refining arrows). Teacher calls on 2–3 groups to explain their model, then leads a focused update:

• Producers change air and water into plant matter that becomes food
• Consumers obtain food by eating producers and/or other consumers
• Decomposers break down dead organisms and return decomposed materials to the environment Students revise their own arrows based on feedback, then add one sentence that answers: “How are the roles connected by matter?”

6. 38–45 min · Exit ticket (quick assessment). Teacher gives a single prompt: “Draw or describe the movement of matter in this ecosystem: plants → (animal) → decomposers → soil/environment. Include where air/water fit.” Students submit an exit ticket with labeled arrows and a complete sentence.

Resources

• Scenario card set (examples of producers, consumers, decomposers for a local ecosystem)
• “Matter Movement Model” printable (role boxes, arrow templates, word bank)
• Sticky notes or feedback slips (“Glow and Grow” checklist)
• Student notebooks or science journals
• Markers/colored pencils for labeling arrows
• Timer or projected countdown for transitions
• Teacher visual anchor diagram of ecosystem roles

Assessment

• During role-matching (Step 2): check accuracy of identifying producers/consumers/decomposers.
• During model construction and gallery walk (Steps 3–4): look for correct arrow direction and inclusion of decomposers returning decomposed materials to the environment.
• Exit ticket (Step 6): evaluate whether students explain matter movement using ecosystem roles and include air/water/soil/environment appropriately (no molecular details).

Differentiation

• Support:
• Provide sentence starters: “Producers make food by using ___ and ___.” “Consumers get food by eating ___.” “Decomposers return ___ to the environment.”
• Offer a partially completed model for students who need scaffolding, with only a few arrows to fill in.
• Allow students to choose from two ecosystem options with clear example organisms.
• Extension:
• Challenge students to add a second consumer (e.g., primary and secondary consumer) while keeping matter flow accurate.
• Ask for an additional “What would happen if decomposers disappeared?” cause-and-effect statement supported by their model.
• EAL/SEN considerations:
• Use picture cues on the word bank (air/water/soil icons) and encourage labeling before writing explanations.
• Pair students strategically so one partner can read the scenario cards while both contribute to the model.