Lesson Plan

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Lesson Plan
Grade: 10 Date: 25/02/2026
Subject: Biology
Lesson Topic: Investigate the factors that influence diffusion: surface area, temperature, concentration gradient and distance.
Learning Objective/s:
  • Describe diffusion and its importance in living organisms.
  • Explain how surface area, temperature, concentration gradient and distance affect diffusion rate.
  • Predict the effect of changing each factor on diffusion using qualitative reasoning.
  • Conduct simple investigations to measure diffusion rates under varying conditions.
  • Analyse experimental data to draw conclusions about factor influence.
Materials Needed:
  • Diffusion chambers or containers
  • Porous membranes of varying surface area and thickness
  • Thermometers or water baths (5 °C, 25 °C, 45 °C)
  • Colored solutes (e.g., salt solution, glucose solution)
  • Rulers or calipers for measuring membrane thickness
  • Stopwatch
  • Data recording sheets / worksheets
  • Projector for diagrams and summary table
 Introduction:
Begin with a quick demonstration: drop a food‑colouring droplet into two beakers of water—one still, one gently stirred—to visualise diffusion. Recall that particles move from high to low concentration and that this process underpins gas exchange and nutrient transport in organisms. Today you will investigate how surface area, temperature, concentration gradient and distance each modify the rate of diffusion, and you will be able to predict the outcome of each manipulation.
Lesson Structure:
  1. Do‑now (5'): Students answer a short question on diffusion in their notebooks (check understanding).
  2. Mini‑lecture (10'): Define diffusion, introduce Fick’s first law, and outline the four factors (use projector).
  3. Group investigations (30'): Four stations—each exploring one factor (surface area, temperature, concentration gradient, distance). Students record the time for colour to appear (teacher circulates).
  4. Data analysis (10'): Groups calculate relative rates and complete a summary table on their worksheet.
  5. Whole‑class discussion (10'): Each group presents findings; class compares results to predicted trends.
  6. Exit ticket (5'): Students write one sentence predicting how a fifth factor (e.g., membrane permeability) would affect diffusion.
Conclusion:
Summarise that increasing surface area or temperature, or steepening the concentration gradient speeds diffusion, while greater distance slows it. For the exit ticket, you noted a prediction about membrane permeability, showing you can extend the concept. For homework, complete the worksheet by applying Fick’s law to a real‑world example such as oxygen exchange in alveoli.