Biology · 12th Grade

Active learning ideas

Interspecific Interactions: Competition and Predation

Active learning works for this topic because interspecific interactions involve dynamic processes like population cycles and niche specialization, which students grasp more deeply through hands-on exploration. Simulations and case studies let students see cause-and-effect relationships in real time, making abstract evolutionary pressures tangible and memorable.

• Common Core State Standards
• HS-LS2-2
• HS-LS2-6

• 25–45 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Simulation Game
• 45 min · Small Groups

Simulation Game: Predator-Prey Population Cycles

Student groups simulate predator and prey populations using cards or beans representing individual organisms. Each round, students calculate survival and reproduction, then adjust population counts. Groups graph population sizes over 10 rounds and identify the phase relationship between predator and prey peaks, comparing their results to Lotka-Volterra model predictions.

Explain how niche partitioning and competition shape community structure.

Facilitation Tip

During the Gallery Walk, provide a graphic organizer with columns for species, resource, and adaptation to guide students' note-taking on niche partitioning examples.

What to look for

Present students with a scenario: 'A new, highly efficient herbivore is introduced into a grassland ecosystem with several native herbivore species.' Ask: 'What are two ways this introduction could impact the existing herbivore community? How might niche partitioning or competitive exclusion play a role?'

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

Activity 02

• Case Study Analysis
• 35 min · Pairs

Case Study Analysis: Yellowstone Trophic Cascade

Pairs read a data summary of wolf reintroduction effects in Yellowstone and construct a cause-and-effect diagram tracing how wolf predation on elk affected riparian vegetation, beaver populations, and stream hydrology. Pairs present their diagrams and compare which indirect effects each pair identified, noting any that were overlooked.

Analyze the evolutionary adaptations that arise from predator-prey relationships.

What to look for

Provide students with a diagram showing two predator species and their shared prey. Ask them to label the types of interactions occurring (e.g., interspecific competition for prey, predation). Then, ask them to write one sentence explaining a potential evolutionary adaptation one of the predators might develop to reduce competition.

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

Activity 03

• Think-Pair-Share
• 25 min · Pairs

Think-Pair-Share: Competitive Exclusion vs. Coexistence

Present data from two species of barnacles occupying different zones on a tidal rock face. Pairs explain which competitive mechanisms are operating, predict what would happen if one species were removed, and design a simple field experiment to test competitive exclusion in this system.

Predict the outcome of introducing a new predator or competitor into an ecosystem.

What to look for

On an index card, have students define 'niche partitioning' in their own words and provide one specific example of how it helps species coexist. They should also list one real-world profession that uses this ecological concept.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

Activity 04

• Gallery Walk
• 40 min · Small Groups

Gallery Walk: Niche Partitioning Examples

Post six stations showing data on niche partitioning in different communities, including MacArthur's warblers, lizard communities, and African savanna grazers. Student groups rotate, identify the resource axis along which each community is partitioned, and classify each as character displacement or ecological niche differentiation.

Explain how niche partitioning and competition shape community structure.

What to look for

Present students with a scenario: 'A new, highly efficient herbivore is introduced into a grassland ecosystem with several native herbivore species.' Ask: 'What are two ways this introduction could impact the existing herbivore community? How might niche partitioning or competitive exclusion play a role?'

• Understand
• Apply
• Analyze
• Create
• Relationship Skills
• Social Awareness

A few notes on teaching this unit

Teachers should avoid oversimplifying the outcome of interspecific interactions, as real ecosystems often show coexistence rather than competitive exclusion. Use real-world examples to show students that outcomes depend on scale, resource abundance, and environmental context. Research suggests students develop stronger conceptual models when they first observe patterns in simulations before analyzing case studies.

By the end of these activities, students should be able to explain how competition and predation shape community structure, use evidence to support claims about niche partitioning, and predict outcomes of species introductions or removals. Look for accurate use of vocabulary and evidence-based reasoning in discussions and written responses.

---

Watch Out for These Misconceptions

• During the Think-Pair-Share: Competitive Exclusion vs. Coexistence, watch for students who assume the strongest competitor will always eliminate others, leading to monocultures in ecosystems.

  Use the Think-Pair-Share to redirect this misconception by having students examine real examples of niche partitioning in the gallery walk images, then revisit their initial assumptions about competition outcomes.

• During the Yellowstone Trophic Cascade Case Study, watch for students who claim predators harm ecosystems by reducing prey populations.

  Use the Yellowstone Case Study to correct this idea by having students analyze the primary literature showing how wolf reintroduction increased biodiversity and vegetation recovery, linking predator regulation to ecosystem health.

• During the Predator-Prey Population Cycles Simulation, watch for students who describe prey species as passive victims, overlooking their role in the evolutionary arms race.

  After the simulation, ask students to brainstorm prey adaptations that could alter the cycle, using the simulation results as evidence for reciprocal evolutionary pressures between predators and prey.

---

Methods used in this brief

• Simulation Game
• Case Study Analysis
• Think-Pair-Share
• Gallery Walk