Science lesson plan · 10th grade (Year 11 in England) · 45 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 · 5 min
- Quick retrieval from earlier learning (Photosynthesis). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- In which part of a plant cell does photosynthesis happen? (nucleus / chloroplasts / vacuole / cell wall) → chloroplastsPrompt: This part contains the green pigment.
- Pondweed in light gives off 12 bubbles of oxygen in 3 minutes. What is the rate in bubbles per minute? → 4Prompt: Rate = amount ÷ time.
- Photosynthesis: which statement is NOT true? (Photosynthesis happens in the roots. / Photosynthesis produces oxygen. / Chlorophyll is found in chloroplasts. / Photosynthesis takes in energy (it is endothermic).) → Photosynthesis happens in the roots.Prompt: Remember the word equation.
Hook · 5 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 · 10 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 · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- On a graph, the rate rises with light intensity and then levels off. Why does it level off? (The plant has died / Another factor, such as CO₂ or temperature, is now limiting / Light stops reaching the leaf / Oxygen runs out) → Another factor, such as CO₂ or temperature, is now limitingPrompt: Adding more light no longer helps. Something else is in short supply.
- Light intensity is inversely proportional to the square of the distance from the lamp. A lamp is moved from 20 cm to 80 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal. → 0.0625Prompt: By what factor did the distance change?
You do: independent practice · 10 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 · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- Why does the rate of photosynthesis fall at very high temperatures? (Enzymes are denatured / Chlorophyll becomes blue / There is too much light / Carbon dioxide turns into oxygen) → Enzymes are denaturedPrompt: Photosynthesis is controlled by proteins that change shape when too hot.
- Light intensity is inversely proportional to the square of the distance from the lamp. A lamp is moved from 20 cm to 80 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal. → 0.0625Prompt: 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