| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: Investigate and state the effect of varying light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis. |
Learning Objective/s:
- Describe the overall photosynthetic equation and the role of chloroplasts.
- Explain how light intensity, CO₂ concentration, and temperature affect the rate of photosynthesis.
- Analyse experimental data to identify optimal conditions and limiting factors.
- Design a simple investigation varying one factor while controlling the others.
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Materials Needed:
- Elodea (or Cabomba) leaf segments
- Test tubes or sealed containers
- Sodium bicarbonate solution (CO₂ source)
- Water bath with temperature control
- Adjustable lamp with lux meter or distance markers
- Gas syringe or graduated cylinder
- Stopwatch and data‑table handouts
- Projector for diagram presentation
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Introduction:
Begin with a quick demonstration: a leaf in water releases bubbles when illuminated, showing photosynthesis in action. Review the basic photosynthetic equation and the three environmental factors that can influence the reaction. Explain that today’s lesson will investigate how light intensity, carbon dioxide concentration, and temperature each affect the rate of oxygen production, and students will be able to predict and justify the observed trends.
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Lesson Structure:
- Do‑Now (5') – Short quiz on the photosynthetic equation and influencing factors; teacher checks responses.
- Mini‑lecture (10') – Review light‑dependent and light‑independent reactions; show experimental set‑up with projected diagram.
- Practical investigation (30') – Groups set up apparatus, vary one factor (e.g., light intensity) while keeping CO₂ and temperature constant, record O₂ volume every 2 min.
- Data analysis (10') – Plot results, identify trends, discuss saturation point.
- Rotate factors (15') – Repeat procedure for CO₂ concentration and temperature using the same data sheet.
- Whole‑class synthesis (10') – Compare graphs, summarise how each factor influences rate and discuss interactions.
- Exit ticket (5') – Write one sentence stating the optimal condition for photosynthesis and one remaining question.
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Conclusion:
Summarise that light intensity, CO₂ concentration, and temperature each have a characteristic effect on photosynthetic rate, with an optimum range where the reaction is fastest. Highlight that the experiment demonstrated limiting factors and the concept of saturation. For homework, ask students to research how different wavelengths of light influence photosynthesis and prepare a brief report.
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