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PlayOwl

Science · Grade 9

Ecological Relationships and Populations

Learners model population growth with exponential and logistic equations, explain carrying capacity with density-dependent and density-independent limiting factors, and analyse predator–prey cycles with a simulation whose rule they take apart. They classify species interactions by their effects on each partner and estimate real population sizes with quadrats and mark–recapture, stating the assumptions behind every estimate.

  • 5 lessons
  • About 125 minutes
  • Populations and interactions check: 12 questions
  • Ways to answer: fill in the blanks, choose an answer, highlight a text, label a picture, match pairs and type a number
See plans Included with Family, Teacher and School plans. Open in PlayOwl

What learners will discover

  • Calculate per-capita growth rates and model exponential and logistic growth, interpreting J-shaped and S-shaped curves.
  • Explain carrying capacity and classify limiting factors as density-dependent or density-independent, including overshoot and changes in carrying capacity.
  • Analyse predator–prey dynamics with a model and data, explaining the lag between predator and prey cycles and the model's limits.
  • Classify species interactions (competition, predation, herbivory, parasitism, mutualism, commensalism) by their effects and explain competitive exclusion.
  • Estimate population size with quadrat sampling and mark–recapture (N = M × C ÷ R) and evaluate the assumptions and sources of error.

Lessons

  1. Exponential and logistic growth 9 steps5 practiceabout 27 min
  2. Limiting factors and carrying capacity 7 steps4 practiceabout 22 min
  3. Predator–prey dynamics 9 steps5 practiceabout 26 min
  4. Species interactions 7 steps4 practiceabout 23 min
  5. Estimating population size 8 steps5 practiceabout 27 min
  6. Populations and interactions check 12 questions at the end

Keep exploring

More 9th grade science

Guide for grown-ups