Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Geography
Lesson Topic: Gersmehl diagrams, soil fertility, energy flows and trophic levels
Learning Objective/s:
  • Construct and interpret Gersmehl diagrams for rainforest and savanna ecosystems.
  • Explain the key factors that maintain soil fertility in each biome.
  • Calculate trophic efficiencies and compare energy flows between the two biomes.
  • Analyse differences in trophic structure and nutrient cycling across biomes.
Materials Needed:
  • Projector and screen
  • Whiteboard and markers
  • Printed worksheets with Gersmehl diagram templates
  • Calculator or spreadsheet software
  • Sample data tables (biomass, nutrient inputs/outputs)
  • Sticky notes for quick checks
 Introduction:
Begin with a striking image of a rainforest canopy and a savanna landscape to hook interest. Ask students what they already know about how nutrients move in these ecosystems. State that by the end of the lesson they will be able to model these flows, compare soil fertility, and evaluate energy transfer across trophic levels.
Lesson Structure:
  1. Do‑Now (5'): Quick mind‑map on “What is nutrient cycling?” – teacher scans for misconceptions.
  2. Mini‑lecture (10'): Overview of nutrient cycling processes and introduction to the Gersmehl equation.
  3. Guided practice (15'): Students work in pairs to fill out a Gersmehl diagram for the rainforest using provided data.
  4. Comparative activity (10'): Same task for the savanna; groups discuss differences in recycling and leaching.
  5. Energy flow calculation (10'): Using the 10 % rule, calculate energy available to herbivores in each biome.
  6. Whole‑class synthesis (5'): Compare trophic structures and discuss implications for biodiversity.
  7. Formative check (5'): Exit ticket – one sentence summarising a key difference between the two biomes.
Conclusion:
Recap the main points: Gersmehl diagrams reveal contrasting nutrient pathways, soil fertility hinges on decomposition and leaching, and energy transfer follows the 10 % rule with biome‑specific efficiencies. Collect exit tickets and assign a short homework task to create a Gersmehl diagram for a third biome (e.g., temperate forest).