Unit Plan 12 (Grade 7 Science): Food Webs & Energy Flow
Grade 7 science unit modeling how energy flows from the sun through food webs and how matter cycles between living organisms and the environment in ecosystems.
Focus: Develop and use models to describe how matter cycles and energy flows among living (producers, consumers, decomposers) and nonliving parts (sunlight, air, water, soil) of ecosystems.
Grade Level: 7
Subject Area: Science (Life Science — Ecosystems & Energy)
Total Unit Duration: 5 sessions (one week), 50–60 minutes per session
I. Introduction
In this unit, students move from who interacts with whom to how matter and energy move through ecosystems. They build and revise food chains and food webs, then layer in energy pyramids and matter cycling (e.g., carbon, nutrients) between organisms and the environment. Using diagrams, arrows, and color-coding, students develop models aligned to MS-LS2-3 showing energy flowing one way (from the sun through organisms and out as heat) while matter cycles repeatedly through living and nonliving parts of the ecosystem.
Essential Questions
- How do food chains and food webs show the movement of energy and matter in ecosystems?
- What is the difference between how energy flows and how matter cycles among organisms and the environment?
- What roles do producers, consumers, and decomposers play in energy transfer and matter cycling?
- How can a model (diagram, web, or pyramid) help us clearly describe the cycling of matter and flow of energy in an ecosystem?
II. Objectives and Standards
Learning Objectives — Students will be able to:
- Identify producers, consumers (herbivores, carnivores, omnivores), and decomposers in an ecosystem and describe their roles in energy transfer and matter cycling.
- Construct food chains and food webs with correctly directed arrows showing energy flow from one organism to another.
- Develop and revise models (food webs, energy pyramids, annotated diagrams) to show energy flow from the sun through producers to consumers and out as heat.
- Describe and model how matter cycles between living things (organisms) and nonliving reservoirs (air, water, soil, detritus) through processes like feeding, death, decomposition, and waste.
- Use their models to explain similarities and differences between energy flow (one-way, decreasing) and matter cycling (repeated, conserved) in ecosystems, meeting MS-LS2-3.
Standards Alignment — 7th Grade (NGSS-based custom)
- MS-LS2-3 — Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.
- Students create and revise food webs, energy pyramids, and matter-cycle diagrams that show these flows and cycles clearly.
Success Criteria — Student Language
- I can identify producers, consumers, and decomposers in an ecosystem and explain what they do.
- I can draw food chains and food webs with arrows that correctly show who gets energy from whom.
- I can explain that energy flows in one direction (from the sun to organisms and out as heat) and is not recycled.
- I can show that matter (like nutrients and carbon) is reused and cycled between living organisms and nonliving parts of the environment.
- I can use my model (diagram/web/pyramid) to clearly explain how matter cycles and energy flows in an ecosystem.