Interactions in Ecosystems

Active learning works for this topic because it turns abstract ecological relationships into tangible experiences. Students move beyond memorizing definitions by physically acting out interactions, which builds empathy for organisms’ roles and clarifies cause-and-effect in ecosystems.

• Year 7
• Science
• 4 activities
• 30 min–50 min

Learning Objectives

1. Compare and contrast competition, predation, and mutualism, commensalism, and parasitism using specific examples.
2. Analyze how predator-prey relationships influence population sizes in a given food web.
3. Predict the cascading effects on an ecosystem if a new invasive species is introduced.
4. Classify symbiotic relationships based on the benefit or harm to each organism involved.

Case Study Analysis

⏱ 45 min·Small Groups

Role-Play: Food Web Drama

Assign students roles as producers, herbivores, carnivores, and apex predators in a simulated ecosystem. Introduce events like resource scarcity or new arrivals, then have them act out interactions while tracking population numbers on charts. Debrief with group predictions of long-term changes.

Prepare & details

Differentiate between competition, predation, and various forms of symbiosis.

Facilitation Tip: For Food Web Drama, assign roles in advance so students prepare relationships rather than improvise, ensuring accurate portrayals.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 30 min·Pairs

Card Sort: Interaction Types

Prepare cards describing scenarios, such as lions hunting zebras or bees pollinating flowers. In pairs, students sort cards into competition, predation, or symbiosis categories, then justify placements with evidence. Extend by creating their own scenarios.

Prepare & details

Analyze how different interactions can influence population dynamics within an ecosystem.

Facilitation Tip: During the Card Sort, circulate and ask pairs to explain why they placed each card in a category, reinforcing reasoning over guessing.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 40 min·Small Groups

Bean Simulation: Population Dynamics

Use beans as organisms: red for predators, white for prey. Students drop and 'eat' beans over rounds, recording counts each time. Discuss how predation rates affect numbers and test variables like introducing competitors.

Prepare & details

Predict the long-term effects of introducing a new predator into an existing food web.

Facilitation Tip: In the Bean Simulation, remind students to record data every round to connect small changes to larger population trends.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Case Study Analysis

⏱ 50 min·Small Groups

Case Study Analysis: Cane Toads Impact

Provide articles on cane toads in Australia. In small groups, map the food web before and after introduction, predict population shifts, and debate management strategies based on interaction types.

Prepare & details

Differentiate between competition, predation, and various forms of symbiosis.

Facilitation Tip: With the Cane Toads Case Study, assign specific roles (scientist, farmer, conservationist) to prompt targeted perspectives in debates.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Teaching This Topic

Experienced teachers approach this topic by grounding abstract concepts in familiar examples and student movement. Avoid starting with definitions—instead, let students discover patterns through role-play and simulations. Research shows that embodied cognition (physically acting out roles) improves retention of ecological relationships by 25%. Focus on iterative cycles: act, analyze, adjust, and repeat to highlight dynamic balance.

What to Expect

Successful learning looks like students confidently distinguishing interaction types, explaining population changes, and justifying their reasoning with evidence from activities. By the end, they should articulate how competition, predation, and symbiosis shape ecosystem balance.

Watch Out for These Misconceptions

Common Misconception

During Card Sort: Interaction Types, watch for students grouping all symbiosis as mutualism.

What to Teach Instead

During Card Sort, ask pairs to justify their mutualism cards using the definition cards. When they place an example like ticks on hosts, prompt them to re-examine the benefits and harms, then reclassify.

Common Misconception

During Bean Simulation: Population Dynamics, watch for students assuming predator populations always increase when prey is abundant.

What to Teach Instead

During Bean Simulation, pause after each round to graph data as a class. Ask, "What happens when prey numbers drop due to predation?" to highlight lag times in population responses.

Common Misconception

During Food Web Drama, watch for students portraying competition only between the same species.

What to Teach Instead

During Food Web Drama, assign roles from different trophic levels (e.g., koalas and possums for competition over eucalyptus leaves) and ask the audience to identify the interaction type during debrief.

Assessment Ideas

Quick Check

After Card Sort: Interaction Types, hand out short scenarios on slips of paper. Students identify the interaction type and their reasoning in 2–3 sentences, then swap with a partner for peer feedback.

Discussion Prompt

After Food Web Drama, pose the question: 'What might happen if the clownfish were removed from the anemone’s ecosystem?' Facilitate a class discussion where students use their role-play experiences to justify predictions about ripple effects.

Exit Ticket

During Bean Simulation, have students sketch a simple graph showing predator and prey numbers over time and label key phases, such as lag, growth, and decline, to assess their understanding of population dynamics.

Extensions & Scaffolding

• Challenge early finishers to design a new scenario with an invasive species and predict its impact on the existing food web, then present to the class.
• Scaffolding: Provide sentence stems for struggling students, such as, "This interaction is ______ because..." during Card Sort discussions.
• Deeper exploration: Have students research a lesser-known symbiotic pair, create a short video explaining the interaction, and share with peers for peer review.

Key Vocabulary

Competition	An interaction between organisms or species in which both are harmed. This occurs when they have the same limited needs, such as food, water, or territory.
Predation	An interaction where one organism, the predator, hunts and kills another organism, the prey, for food. This shapes the populations of both species.
Symbiosis	A close, long-term interaction between two different biological species. This can be beneficial, neutral, or detrimental to one or both species.
Mutualism	A type of symbiotic relationship where both interacting species benefit. For example, bees pollinating flowers while collecting nectar.
Parasitism	A symbiotic relationship where one organism, the parasite, benefits at the expense of the other organism, the host. For instance, ticks feeding on a dog.