Science · 7th Grade

Active learning ideas

Energy Flow in Ecosystems

Explore the hidden connections that power life on Earth. We'll trace the incredible journey of energy as it flows from the sun to plants, animals, and back to the soil.

• Common Core State Standards
• NGSS: MS-LS2 - Ecosystems: Interactions, Energy, and Dynamics - Developing a Model to Describe the Flow of Energy

• 30–60 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Simulation Game
• 30 min · Whole Class

Food Web Yarn Activity

Assign each student a role as a producer, consumer, or decomposer in a specific ecosystem. Students toss a ball of yarn to connect themselves to the organisms they eat or are eaten by, creating a physical representation of a food web.

Explain the role of producers, consumers, and decomposers in an ecosystem's energy flow.

Facilitation Tip

After the web is built, gently tug on one student's string (e.g., the 'grass') to demonstrate how the entire ecosystem is affected.

What to look for

Exit Ticket: Students draw a four-organism food chain, label each organism with its role (producer, primary consumer, etc.), and draw arrows showing the correct direction of energy flow.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 02

• Simulation Game
• 45 min · Small Groups

Energy Pyramid Construction

Using building blocks or paper cutouts, students construct a physical energy pyramid. Each level should be proportionally smaller to represent the 10% rule of energy transfer, with the largest base for producers.

Analyze how the removal of a top predator would impact the structure of a food web.

Facilitation Tip

Have groups label each trophic level and calculate the amount of energy available if the producers start with 10,000 kcal.

What to look for

Food Web Project: Students research a specific ecosystem (e.g., desert, rainforest, local pond) and create a detailed poster or digital presentation of its food web, explaining the roles of key organisms and the flow of energy.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 03

• Simulation Game
• 60 min · Pairs

Owl Pellet Dissection Lab

Students carefully dissect sterilized owl pellets to identify and sort the bones of prey animals. They then use their findings to reconstruct the owl's food chain and make inferences about its role in the local food web.

Compare the efficiency of energy transfer between different trophic levels in an energy pyramid.

Facilitation Tip

Provide bone identification charts to help students classify their findings and reduce frustration.

What to look for

Students use a rubric to review a food web they created, checking for correct arrow direction, inclusion of producers and decomposers, and at least two different trophic levels for consumers.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

Activity 04

• Simulation Game
• 50 min · Individual

Digital Ecosystem Modeler

Using a simple simulation or drawing tool, students create a digital model of a food web. They can then predict and test what happens when one population is removed or a new species is introduced.

Explain the role of producers, consumers, and decomposers in an ecosystem's energy flow.

Facilitation Tip

Encourage students to model a local ecosystem to connect the learning to their own environment.

What to look for

Exit Ticket: Students draw a four-organism food chain, label each organism with its role (producer, primary consumer, etc.), and draw arrows showing the correct direction of energy flow.

• Apply
• Analyze
• Evaluate
• Create
• Social Awareness
• Decision-Making

A few notes on teaching this unit

Begin with a simple, relatable food chain, like sun -> grass -> grasshopper -> bird. Use arrows and explicitly state, 'The arrow shows where the energy goes'. After students master this, introduce overlapping chains to build a food web. Use visuals and analogies, like a charging cable for energy flow, to make the abstract concepts concrete.

Students will be able to diagram food webs and explain how every organism, from the smallest microbe to the largest predator, plays a crucial role in the transfer of energy.

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Watch Out for These Misconceptions

• Plants get their 'food' from the soil.

  Plants create their own food (glucose, a sugar) through photosynthesis using sunlight, water, and carbon dioxide. The soil provides essential nutrients and water, but not the energy-rich food itself.

• Energy is recycled in an ecosystem, just like nutrients.

  Energy flows in one direction through an ecosystem and is lost as heat at each trophic level. It is not recycled. Matter, such as carbon and nitrogen, is recycled by decomposers.

• Arrows in a food chain point from the eater to what it eats.

  The arrows in a food chain or food web represent the direction of energy flow. Therefore, they point from the organism being eaten to the organism that eats it.

• Decomposers are at the 'bottom' of the food chain and are not very important.

  Decomposers are essential to every ecosystem. They break down dead organic matter from all trophic levels, recycling nutrients back into the environment so producers can use them.

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Methods used in this brief

• Simulation Game