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.
- Which is a use of the glucose made in photosynthesis? (It makes chlorophyll green. / It is turned into soil. / It is stored as starch. / It is breathed out.) → It is stored as starch.Prompt: Iodine turns blue-black when this store is present.
- Pondweed in light gives off 54 bubbles of oxygen in 3 minutes. What is the rate in bubbles per minute? → 18Prompt: Rate = amount ÷ time.
- Photosynthesis: which statement is NOT true? (Photosynthesis needs light. / Chlorophyll is found in chloroplasts. / Photosynthesis takes in energy (it is endothermic). / Photosynthesis turns oxygen into carbon dioxide.) → Photosynthesis turns oxygen into carbon dioxide.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 60 cm from a plant. The new light intensity is what fraction of the old one? Give a decimal. → 0.1111Prompt: 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.
- 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 40 cm than at 30 cm? → 2.5Prompt: Read both values from the table.
- On a graph, the rate rises with light intensity and then levels off. Why does it level off? (Oxygen runs out / The plant has died / Another factor, such as CO₂ or temperature, is now limiting / Light stops reaching the leaf) → Another factor, such as CO₂ or temperature, is now limitingPrompt: Adding more light no longer helps. Something else is in short supply.
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