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Science lesson plan · 10th grade (Year 11 in England) · 60 minutes

Rate of photosynthesis and limiting factors

Plants

CCSS NGSS.HS-LS1-5England: KS4 Combined Science: Photosynthesis

Objective and success criteria

Students will: Rate of photosynthesis and limiting factors.

  • 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: Photosynthesis

Leads to: the next skill in this area.

Materials: Real plants or seeds, Hand lenses, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).

Warm-up · 6 min

  • Quick retrieval from earlier learning (Photosynthesis). Students answer on mini whiteboards.
  • Show answers together and note who needs support in the main task.
  1. Complete the word equation: carbon dioxide + ___ → glucose + oxygen (water / soil / oxygen / glucose) → waterPrompt: The roots take this in.
  2. Pondweed in light gives off 52 bubbles of oxygen in 4 minutes. What is the rate in bubbles per minute? → 13Prompt: Rate = amount ÷ time.
  3. Photosynthesis: which statement is NOT true? (Photosynthesis turns oxygen into carbon dioxide. / Photosynthesis takes in energy (it is endothermic). / Photosynthesis produces oxygen. / Photosynthesis needs light.) → Photosynthesis turns oxygen into carbon dioxide.Prompt: Remember the word equation.

Hook · 6 min

  • Bring in a plant that has been kept in the dark next to one in the light, and ask what happened.
  • Share the objective: Rate of photosynthesis and limiting factors. 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: Which of these is NOT a limiting factor for photosynthesis?
  • Step 1: The main limiting factors are light intensity, carbon dioxide concentration and temperature.
  • Step 2: So the answer is: oxygen concentration
  • Answer: oxygen concentration
  • 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. Why does the rate of photosynthesis fall at very high temperatures? (There is too much light / Enzymes are denatured / Carbon dioxide turns into oxygen / Chlorophyll becomes blue) → Enzymes are denaturedPrompt: Photosynthesis is controlled by proteins that change shape when too hot.
  2. Light intensity is inversely proportional to the square of the distance from the lamp. A lamp is moved from 25 cm to 50 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal. → 0.25Prompt: By what factor did the distance change?

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. Bubbles per minute from pondweed at different lamp distances: 10 cm: 67 20 cm: 16.8 30 cm: 7.4 40 cm: 4.2 50 cm: 2.7 How many fewer bubbles per minute were counted at 50 cm than at 40 cm? → 1.5Prompt: Read both values from the table.
  2. Light intensity is inversely proportional to the square of the distance from the lamp. A lamp is moved from 20 cm to 40 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal. → 0.25Prompt: By what factor did the distance change?

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: Photosynthesis.
  • Use concrete materials: real plants or seeds.
  • 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-10.

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

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Rate of photosynthesis and limiting factors

Name

Date

Score/ 8

  1. Question 1

    Bubbles per minute from pondweed at different lamp distances: 10 cm: 50 20 cm: 12.5 30 cm: 5.6 40 cm: 3.1 50 cm: 2 How many fewer bubbles per minute were counted at 50 cm than at 40 cm?

    Answer

  2. Question 2

    Which of these is NOT a limiting factor for photosynthesis?

    • A. light intensity
    • B. oxygen concentration
    • C. temperature
    • D. carbon dioxide concentration

  3. Question 3

    Light intensity is inversely proportional to the square of the distance from the lamp. A lamp is moved from 25 cm to 100 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal.

    Answer

  4. Question 4

    Bubbles per minute from pondweed at different lamp distances: 10 cm: 52 20 cm: 13 30 cm: 5.8 40 cm: 3.3 50 cm: 2.1 How many fewer bubbles per minute were counted at 50 cm than at 40 cm?

    Answer

  5. Question 5

    On a graph, the rate rises with light intensity and then levels off. Why does it level off?

    • A. The plant has died
    • B. Oxygen runs out
    • C. Another factor, such as COâ‚‚ or temperature, is now limiting
    • D. Light stops reaching the leaf

  6. Question 6

    Light intensity is inversely proportional to the square of the distance from the lamp. A lamp is moved from 25 cm to 75 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal.

    Answer

  7. Question 7

    Bubbles per minute from pondweed at different lamp distances: 10 cm: 68 20 cm: 17 30 cm: 7.6 40 cm: 4.3 50 cm: 2.7 How many fewer bubbles per minute were counted at 30 cm than at 20 cm?

    Answer

  8. Question 8

    Farmers add paraffin heaters to greenhouses in winter. Which two factors does this increase?

    • A. temperature and carbon dioxide
    • B. light and oxygen
    • C. water and oxygen
    • D. light and water

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Answer key: Rate of photosynthesis and limiting factors

  1. 1. 1.1

  2. 2. B. oxygen concentration

  3. 3. 0.0625

  4. 4. 1.2

  5. 5. C. Another factor, such as COâ‚‚ or temperature, is now limiting

  6. 6. 0.1111

  7. 7. 9.4

  8. 8. A. temperature and carbon dioxide