Lesson Plan

• Describe how leaf structural features influence transpiration rates.
• Explain the role of stomata, cuticle, leaf orientation, and trichomes in water vapour loss.
• Analyse the relationship between stomatal conductance and vapour pressure deficit.
• Compare how different leaf adaptations affect water‑use efficiency.
• Apply knowledge to predict transpiration changes under varying environmental conditions.

• Projector and screen for slides/diagrams
• Printed worksheet with leaf diagram and data table
• Microscopes or hand lenses for leaf sample observation
• Sample leaves of different species (broadleaf, needleleaf, etc.)
• Whiteboard and markers
• Sticky notes for exit tickets

Begin with a striking image of a desert cactus and ask, “How does this plant survive with so little water?” Connect to students’ prior knowledge of photosynthesis and gas exchange. Explain that today they will uncover the leaf structures that control water loss and the criteria for success: being able to link each structure to its effect on transpiration.

1. Do‑Now (5'): Students list all leaf parts they recall on a sticky note; quick share.
2. Mini‑lecture with slide diagram (10'): Introduce stomata, cuticle, trichomes, orientation, surface area; emphasize their impact on transpiration.
3. Microscope/hand‑lens activity (15'): Examine prepared leaf slides; record observations of stomatal density and trichomes on worksheet.
4. Concept‑mapping (10'): In pairs, create a map linking each leaf feature to its effect on water loss and CO₂ uptake.
5. Guided practice (5'): Solve a short problem using the equation E = gₛ × VPD, interpreting how structural changes alter E.
6. Check for Understanding (5'): Quick quiz via Kahoot or show of hands on key concepts.

Summarise that leaf structure fine‑tunes the balance between CO₂ acquisition and water loss. Students complete an exit ticket stating one leaf adaptation and its specific effect on transpiration. For homework, assign a brief research task: find a plant adapted to arid conditions and explain how its leaf morphology supports water conservation.