Activity 01
Simulation Game: Predator-Prey Cycles
Scatter 100 beans as prey on the floor. Pairs act as predators collecting 10 beans per round in 1 minute, then add prey based on survivors. Graph population changes over 10 rounds. Discuss cycles and regulation.
Compare the effects of interspecific and intraspecific competition on populations.
Facilitation TipFor the Simulation Game, rotate students through predator and prey roles every two minutes to ensure everyone experiences both pressures.
What to look forPresent students with two scenarios: 1) A group of deer competing for limited grass. 2) Eagles and hawks competing for the same rodent prey. Ask students to identify the type of competition in each scenario and explain one potential outcome for the populations involved.
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Activity 02
Relay: Resource Competition
Set limited resource cards (food, space) at stations. Small groups relay to claim cards, competing intraspecifically within groups or interspecifically between groups. Tally survivors and note effects on 'population' sizes. Reflect on winners and losers.
Analyze how predator-prey relationships regulate population sizes.
Facilitation TipIn the Resource Competition Relay, place a few 'mating partners' or 'territories' as hidden resources to push students beyond food-focused thinking.
What to look forPose the question: 'Imagine the monitor lizards, a key predator in some Singaporean ecosystems, were suddenly removed. What are two specific changes you would expect to see in the populations of other animals and plants in that area, and why?' Facilitate a class discussion to explore cause and effect.
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Activity 03
Data Analysis: Lynx-Hare Graphs
Provide historical population data tables. In small groups, students plot line graphs for predator and prey over decades. Identify peaks, lags, and crashes, then predict outcomes without predators.
Predict the long-term consequences for an ecosystem if a key predator is removed.
Facilitation TipDuring the Data Analysis activity, have students annotate the lynx-hare graph with population highs and lows before sharing their observations.
What to look forOn an index card, students will draw a simple diagram showing either an intraspecific or interspecific competition scenario. Below the diagram, they will write one sentence explaining the interaction and one sentence predicting a consequence for one of the organisms.
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Activity 04
Role-Play: Ecosystem Disruption
Assign roles in a food web: prey, predators, plants. Whole class acts out normal balance, then removes a predator. Observe chain reactions like prey overgrowth and plant depletion. Debrief predictions.
Compare the effects of interspecific and intraspecific competition on populations.
Facilitation TipIn the Role-Play, assign students to record predicted outcomes on chart paper before acting out the scenario to hold them accountable for initial hypotheses.
What to look forPresent students with two scenarios: 1) A group of deer competing for limited grass. 2) Eagles and hawks competing for the same rodent prey. Ask students to identify the type of competition in each scenario and explain one potential outcome for the populations involved.
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Generate Complete Lesson→A few notes on teaching this unit
Teachers should avoid over-simplifying these relationships by framing them as static or linear, which research shows leads to misconceptions. Instead, use time-bound simulations to emphasize lags, such as how prey populations rebound before predators recover. Encourage students to revisit their initial predictions after each activity to refine their understanding through iterative feedback.
Successful learning looks like students accurately describing how resource availability and predation pressure drive population changes, using evidence from simulations, graphs, or role-play discussions. They should also identify the type of competition or predator-prey relationship in new scenarios without prompting.
Watch Out for These Misconceptions
During the Simulation Game: Predator-Prey Cycles, watch for students assuming predators immediately eliminate prey. Redirect by asking, 'What happens to the predator population when prey numbers drop too low?' and have them adjust their token counts accordingly.
During the Simulation Game: Predator-Prey Cycles, emphasize the lag between predator decline and prey rebound by pausing after each round to graph the populations on the board and discuss why the cycles form.
During the Relay: Resource Competition, watch for students focusing only on food as the sole resource. Redirect by adding a 'territory' or 'mating partner' station and ask, 'How might space or mates change the competition outcome?'
During the Relay: Resource Competition, have students compare their final population sizes with peers who had different resource distributions to highlight how competition extends beyond food.
During the Role-Play: Ecosystem Disruption, watch for students assuming removing a predator always helps the ecosystem. Redirect by asking, 'What happens to the prey’s food supply when their numbers explode?' and have them act out the consequences.
During the Role-Play: Ecosystem Disruption, require students to present their predicted chain reactions (e.g., overgrazing, plant death) to the class and defend their reasoning with evidence from the role-play.
Methods used in this brief