Biotic Limiting Factors: Competition & Predation

Active learning helps students grasp biotic limiting factors because competition and predation are dynamic processes best understood through firsthand experience. Movement-based simulations and role-playing create visceral memories of population regulation, making abstract concepts tangible for learners who struggle with static examples.

• Grade 7
• Science
• 4 activities
• 35 min–50 min

Learning Objectives

1. Compare and contrast intraspecific and interspecific competition using specific examples of resource limitation.
2. Analyze data from predator-prey population graphs to explain how each population regulates the other.
3. Predict the potential impact on an ecosystem's carrying capacity if a new predator is introduced.
4. Explain the role of competition and predation in maintaining the carrying capacity of a given habitat.

Ready-to-Use Activities

Simulation Game

⏱ 45 min·Pairs

Simulation Game: Predator-Prey Chase

Scatter 100 beans (prey) on the floor; pairs act as predators collecting beans in 1-minute rounds while 'prey' decreases each round. Graph population changes over 10 rounds. Discuss how predation limits prey growth.

Prepare & details

Differentiate between interspecific and intraspecific competition.

Facilitation Tip: During the Predator-Prey Chase, adjust the playing field size or starting prey/predator ratios to match your class size, ensuring no student waits too long between turns.

Setup: Flexible space for group stations

Materials: Role cards with goals/resources, Game currency or tokens, Round tracker

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

Stations Rotation

⏱ 50 min·Small Groups

Stations Rotation: Competition Scenarios

Set up stations with limited resources: food bowls for intraspecific (same animal cutouts), territory maps for interspecific (different species). Small groups compete, record winners, and rotate. Compare outcomes in class share-out.

Prepare & details

Analyze how predator-prey relationships regulate population sizes.

Facilitation Tip: For the Station Rotation, assign each group a scenario card with clear roles and resources, then circulate to ask probing questions like 'What would happen if one competitor left the area?'

Setup: Tables/desks arranged in 4-6 distinct stations around room

Materials: Station instruction cards, Different materials per station, Rotation timer

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Case Study Analysis

⏱ 35 min·Individual

Data Analysis: Lynx-Hare Graphs

Provide historical population graphs; individuals plot trends, identify cycles, and predict effects of removing predators. Pairs present predictions with evidence from data.

Prepare & details

Predict the long-term effects of introducing a new predator into an ecosystem.

Facilitation Tip: When analyzing the Lynx-Hare graphs, provide colored pencils and have students trace the peaks and valleys together, labeling each phase to reinforce the cyclical nature of population changes.

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·Whole Class

Role-Play: New Predator Introduction

Whole class divides into prey, original predators, and new predators. Simulate hunts over rounds, adjusting numbers based on 'success.' Debrief on ecosystem changes.

Prepare & details

Differentiate between interspecific and intraspecific competition.

Facilitation Tip: In the New Predator Introduction role-play, give students five minutes to prepare arguments for or against the predator’s introduction, then guide a structured debate to surface multiple perspectives.

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

Teachers should begin with simple, low-stakes simulations to build intuition before introducing mathematical models. Avoid overwhelming students with jargon; instead, use terms like 'crowding' or 'chase' during activities, then connect these experiences to scientific vocabulary afterward. Research shows that students retain predator-prey dynamics better when they physically embody the roles, so prioritize movement and repetition over static lectures.

What to Expect

Successful learning looks like students accurately distinguishing intraspecific from interspecific competition, explaining predator-prey cycles using evidence from simulations, and predicting ecosystem impacts when new species are introduced. Small-group discussions should reveal growing confidence in applying these concepts to unfamiliar scenarios.

Watch Out for These Misconceptions

Common Misconception

During the Station Rotation, watch for students who assume competition only happens between different species when observing their assigned scenarios.

What to Teach Instead

Redirect their attention to the identical 'animals' in their group and ask, 'What happens to your food pile when more of your own species arrive?' to highlight intraspecific competition.

Common Misconception

During the Predator-Prey Chase, watch for students who believe predator populations always outnumber prey.

What to Teach Instead

Pause the game and have students count the remaining prey and predators, then ask, 'Why do you think the prey numbers dropped so low?' to reveal the cyclical relationship.

Common Misconception

During the New Predator Introduction role-play, watch for students who assume adding any predator will stabilize the ecosystem.

What to Teach Instead

Ask groups to present their predicted outcomes, then challenge them with, 'What if this predator also competes with the fox for shelter?' to uncover unintended interactions.

Assessment Ideas

Quick Check

After the Station Rotation, present students with two scenarios: 1) Squirrels competing for acorns in a forest, and 2) A fox hunting rabbits. Ask students to identify which scenario represents intraspecific competition and which represents interspecific competition, and to justify their answers using details from their station work.

Discussion Prompt

During the Predator-Prey Chase, pose the question: 'Imagine a new, highly effective predator is introduced to an area with rabbits and foxes. What are two possible outcomes for the rabbit population and two possible outcomes for the fox population? Facilitate a class discussion on their predictions, referencing the simulation’s data patterns to support reasoning.

Exit Ticket

After the Lynx-Hare Graphs activity, ask students to draw a simple diagram illustrating a predator-prey relationship. They should label the predator and prey and write one sentence explaining how this interaction affects the population size of the prey, using terms like 'cycles' or 'regulation' from their analysis.

Extensions & Scaffolding

• Challenge: Ask early finishers to design a new predator with specific adaptations and predict its impact on the existing food web using the simulation framework.
• Scaffolding: Provide sentence stems for struggling students, such as 'In this scenario, the _____ population is limited by _____ because...' during the Station Rotation.
• Deeper exploration: Have students research a real-world example of competition or predation, then present their findings using the simulation’s data collection format as a model.

Key Vocabulary

Intraspecific Competition	Competition for resources that occurs between individuals of the same species. This can include competition for food, water, mates, or territory.
Interspecific Competition	Competition for resources that occurs between individuals of different species. This can happen when species share a limited resource, like food or living space.
Predation	An interaction where one organism, the predator, hunts and kills another organism, the prey, for food. This relationship influences the population sizes of both species.
Carrying Capacity	The maximum population size of a biological species that can be sustained in that specific environment, given the available resources and environmental conditions.