Lesson Plan

• Describe how light intensity influences the rate of photosynthesis.
• Explain the effect of carbon dioxide concentration on photosynthetic rate.
• Analyse the impact of temperature on enzyme activity in photosynthesis.
• Interpret experimental data to identify limiting factors.
• Evaluate how limiting factors affect plant productivity.

• Projector and screen
• PowerPoint slides summarising theory
• Gas syringes and sealed leaf‑disc chambers
• Leaf discs (1 cm) and fresh plant material
• Light meter (µmol m⁻² s⁻¹)
• CO₂ source (e.g., NaHCO₃ solution) and delivery system
• Water bath or temperature controller
• Data tables, graph paper or spreadsheet software
• Safety goggles and gloves

Begin with a striking image of a sun‑lit forest canopy to capture interest. Ask students what they think limits a plant’s growth in different environments, linking to prior knowledge of photosynthesis. Explain that today they will investigate how light, CO₂ and temperature each control the rate of photosynthesis and identify success criteria: predict trends, analyse graphs, and draw conclusions.

1. Do‑now (5'): Students sketch the basic photosynthesis equation and list factors they think could affect its rate.
2. Mini‑lecture (10'): Review the three limiting factors, show characteristic rate curves, and discuss the underlying biochemistry.
3. Demonstration (15'): Conduct a quick live demo varying light intensity on leaf discs, recording O₂ evolution with a gas syringe.
4. Group investigation (20'): Teams design a simple experiment for one variable using provided data tables; teacher circulates.
5. Data analysis (10'): Teams plot results, identify plateau regions, and answer guided questions.
6. Whole‑class discussion (10'): Groups share findings; teacher highlights connections to crop yield and climate change.
7. Check for understanding (5'): Exit ticket – one sentence describing the optimal condition for each factor.

Summarise that each factor boosts photosynthetic rate only up to a specific limit, after which another factor becomes limiting. Students complete an exit ticket stating the limiting factor for each graph shown. Assign homework to research how farmers manipulate light, CO₂, or temperature to maximise yields.