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Science lesson plan · 11th grade (Year 12 in England) · 30 minutes

Population growth and carrying capacity

Ecosystems and food chains

CCSS NGSS.HS-LS2-1CCSS NGSS.HS-LS2-2CCSS NGSS.SEP 5England: GCSE Combined Science: Ecology

Objective and success criteria

Students will: Population growth and carrying capacity.

  • I can answer questions on today's skill on my own, without help.
  • I can explain each step and say why it works.
  • I can check my answer and spot a mistake.

Before and after

Needs first: Living and non-living factors in an ecosystem

Leads to: the next skill in this area.

Materials: Food web cards, Arrows to build chains, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 4 min

  • Quick retrieval from earlier learning (Living and non-living factors in an ecosystem). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Is this a biotic or an abiotic factor: a new predator? (abiotic (non-living) / biotic (living)) → biotic (living)Prompt: Does it come from a living organism?
  2. Students placed quadrats in a line leading out from under a tree. Light intensity (% of full sunlight) → number of daisies: 10 % → 2 30 % → 7 50 % → 12 70 % → 17 90 % → 22 Which conclusion do the data support? (Daisies grow best in the shade. / More daisies grow where light intensity is higher. / Light has no link with the number of daisies. / The data prove that light is the only factor that matters.) → More daisies grow where light intensity is higher.Prompt: Look at how the number of daisies changes as light changes.
  3. Lichens grow less well near busy roads. Which abiotic factor is the likely cause? (air pollution such as nitrogen dioxide / a new disease / competition with trees / the number of predators) → air pollution such as nitrogen dioxidePrompt: Lichens are used as indicators of air quality.

Hook · 3 min

  • Show a food web and ask what would happen if one animal disappeared.
  • Share the objective: Population growth and carrying capacity. Read the success criteria together.

I do: model it · 7 min

  • Work through the example out loud, saying why you do each step, not just what you do.
  • Example: A population of yeast cells (thousands per cm³) was counted each day: 15, 30, 60, 114, 186, 246, 285, 300, 297. Which value is closest to the carrying capacity?
  • Step 1: The population stops growing at about 300.
  • Step 2: So the answer is: 300
  • Answer: 300
  • Pause after each step and ask a student to say what comes next.

We do: guided practice · 6 min

  • Do these together. Students try each step on whiteboards before you reveal it.
  • Use the hints as prompts rather than giving the answer.
  1. A population of yeast cells (thousands per cm³) was counted each day: 8, 15, 30, 57, 93, 123, 143, 150, 149. Which value is closest to the carrying capacity? (57 / 75 / 150 / 300) → 150Prompt: The carrying capacity is where the population levels off.
  2. A deer population grew from 1000 to 1200 in one year. What was the percentage growth rate? → 20 %Prompt: Find the increase.

You do: independent practice · 7 min

  • Students work on the student sheet. Circulate and check the first two answers of every student early.
  • Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

Exit ticket · 3 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A population of yeast cells (thousands per cm³) was counted each day: 9, 18, 36, 68, 112, 148, 171, 180, 178. Which value is closest to the carrying capacity? (68 / 90 / 180 / 360) → 180Prompt: The carrying capacity is where the population levels off.
  2. A deer population grew from 500 to 550 in one year. What was the percentage growth rate? → 10 %Prompt: Find the increase.

Watch out for

  • Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
  • Remembering facts without the reason: ask "why?" and "what is the evidence?"

Support and stretch

Support

  • Review first: Living and non-living factors in an ecosystem.
  • Use concrete materials: food web cards.
  • Give the first step of each question, or a partly worked example to finish.
  • Pair with a confident partner for the guided practice.

Stretch

  • Explain a common mistake in writing and how to fix it.
  • Write a word problem that uses today's skill, then solve a partner's.

Homework and more practice

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-11.

Free lesson plan from eurekami.com/lesson-plan-builder

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Population growth and carrying capacity

Name

Date

Score/ 6

  1. Question 1

    A population of yeast cells (thousands per cm³) was counted each day: 25, 50, 100, 190, 310, 410, 475, 500, 495. Which value is closest to the carrying capacity?

    • A. 190
    • B. 250
    • C. 500
    • D. 1000

  2. Question 2

    A deer population grew from 800 to 880 in one year. What was the percentage growth rate?

    Answer%

  3. Question 3

    Why does a population stop growing when it reaches carrying capacity?

    • A. The population runs out of DNA
    • B. Carrying capacity is always 100
    • C. The animals decide to stop breeding
    • D. Limiting factors such as food, space and disease balance births and deaths

  4. Question 4

    A population of yeast cells (thousands per cm³) was counted each day: 15, 30, 60, 114, 186, 246, 285, 300, 297. Which value is closest to the carrying capacity?

    • A. 114
    • B. 150
    • C. 300
    • D. 600

  5. Question 5

    A deer population grew from 1000 to 1100 in one year. What was the percentage growth rate?

    Answer%

  6. Question 6

    Snowshoe hare and lynx populations rise and fall in cycles, with lynx peaks just after hare peaks. Why?

    • A. The two species never interact
    • B. Lynx and hares compete for grass
    • C. More hares feed more lynx; then lynx eat so many hares that hare numbers fall
    • D. Hares eat lynx

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Answer key: Population growth and carrying capacity

  1. 1. C. 500

  2. 2. 10 %

  3. 3. D. Limiting factors such as food, space and disease balance births and deaths

  4. 4. C. 300

  5. 5. 10 %

  6. 6. C. More hares feed more lynx; then lynx eat so many hares that hare numbers fall