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Science lesson plan · 11th grade (Year 12 in England) · 60 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 · 6 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 % → 1 30 % → 3 50 % → 5 70 % → 7 90 % → 9 Which conclusion do the data support? (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. / The tree eats the daisies.) → More daisies grow where light intensity is higher.Prompt: Look at how the number of daisies changes as light changes.
  3. Grey squirrels were introduced to Britain and red squirrel numbers fell. What kind of factor are the grey squirrels for the red squirrels? (biotic: competition and disease / abiotic: temperature / not a factor at all / abiotic: soil pH) → biotic: competition and diseasePrompt: Are grey squirrels alive?

Hook · 6 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 · 12 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 · 12 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: 15, 30, 60, 114, 186, 246, 285, 300, 297. Which value is closest to the carrying capacity? (114 / 150 / 300 / 600) → 300Prompt: The carrying capacity is where the population levels off.
  2. A deer population grew from 400 to 480 in one year. What was the percentage growth rate? → 20 %Prompt: Find the increase.

You do: independent practice · 17 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 8 questions are on the student sheet below, with answers in the key.

Exit ticket · 7 min

  • Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
  1. A deer population grew from 400 to 440 in one year. What was the percentage growth rate? → 10 %Prompt: Find the increase.
  2. A population with plenty of resources and no predators grows… (in a straight line / exponentially (faster and faster) / not at all / more slowly each year) → exponentially (faster and faster)Prompt: Each new individual can also reproduce.

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/ 8

  1. Question 1

    A population with plenty of resources and no predators grows…

    • A. not at all
    • B. exponentially (faster and faster)
    • C. in a straight line
    • D. more slowly each year

  2. Question 2

    A deer population grew from 400 to 420 in one year. What was the percentage growth rate?

    Answer%

  3. Question 3

    A population of yeast cells (thousands per cm³) was counted each day: 10, 20, 40, 76, 124, 164, 190, 200, 198. Which value is closest to the carrying capacity?

    • A. 76
    • B. 100
    • C. 200
    • D. 400

  4. Question 4

    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. Hares eat lynx
    • C. More hares feed more lynx; then lynx eat so many hares that hare numbers fall
    • D. Lynx and hares compete for grass

  5. Question 5

    A deer population grew from 1000 to 1050 in one year. What was the percentage growth rate?

    Answer%

  6. Question 6

    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?

    • A. 68
    • B. 90
    • C. 180
    • D. 360

  7. Question 7

    An invasive species arrives on an island with no predators. What is most likely at first?

    • A. native species grow faster
    • B. the invasive species dies out at once
    • C. rapid population growth that may harm native species
    • D. nothing changes

  8. Question 8

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

    Answer%

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Answer key: Population growth and carrying capacity

  1. 1. B. exponentially (faster and faster)

  2. 2. 5 %

  3. 3. C. 200

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

  5. 5. 5 %

  6. 6. C. 180

  7. 7. C. rapid population growth that may harm native species

  8. 8. 10 %