Lesson Plan

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Lesson Plan
Grade: Date: 17/01/2026
Subject: Chemistry
Lesson Topic: Describe and explain diffusion in terms of kinetic particle theory
Learning Objective/s:
  • Describe diffusion as the net movement of particles from high to low concentration.
  • Explain diffusion using the principles of the kinetic particle theory.
  • Identify and rank factors that affect the rate of diffusion.
  • Compare diffusion rates in gases, liquids and solids.
  • Apply the concepts to predict how temperature changes influence diffusion speed.
Materials Needed:
  • Projector or interactive whiteboard
  • Whiteboard and markers
  • Shallow tray, water, food‑colouring
  • Thermometer or hot plate for gentle heating
  • Stopwatch
  • Handout with key points and diagram
  • Worksheet for practice questions
 Introduction:
Begin with a quick demonstration of a coloured drop spreading in water to capture curiosity. Review students’ prior knowledge of particle motion and concentration gradients. Explain that today they will describe diffusion and link it to the kinetic particle theory, with success measured by their ability to explain the factors influencing its rate.
Lesson Structure:
  1. Do‑now (5') – Students answer: “What happens when two gases are mixed?” to activate prior knowledge.
  2. Mini‑lecture (10') – Define diffusion and present the kinetic particle theory explanation with slides.
  3. Interactive discussion (5') – Students list factors affecting diffusion; teacher confirms with examples.
  4. Demonstration (10') – Perform the coloured‑water experiment, timing diffusion at room temperature then after gentle heating.
  5. Guided analysis (8') – Record observations, calculate relative rates, and relate them to temperature and particle size.
  6. Group activity (10') – Complete a worksheet comparing diffusion in gas, liquid, solid and predicting outcomes for different conditions.
  7. Check for understanding (5') – Quick exit‑ticket quiz with three short questions.
  8. Recap & homework (2') – Summarise key points; assign a short write‑up on a real‑life diffusion example.
Conclusion:
Summarise how kinetic particle theory explains diffusion and the main factors that influence its speed. Have students complete an exit ticket describing one factor and its effect. For homework, ask them to find a real‑life example of diffusion and explain it using the concepts learned.