Lesson Plan

• Describe diffusion as the passive movement of particles from high to low concentration.
• Explain that the kinetic energy of molecules and ions supplies the energy for diffusion.
• Analyse how temperature, particle size and concentration gradient influence diffusion rate.
• Apply the concept to biological examples such as gas exchange and ion transport.
• Predict the effect of changing temperature on diffusion in a given scenario.

• Projector and screen
• Whiteboard and markers
• Diagram handout of diffusion
• Worksheet with self‑check questions
• Coloured beads or particles for a demo
• Two beakers of water at different temperatures
• Thermometer
• Computer with diffusion simulation (optional)

Begin with the question, “What drives the scent of perfume to spread across a room?” Connect this to students’ prior knowledge of concentration gradients. Explain that today they will discover the hidden energy source that powers this movement and will be able to state the success criteria: define diffusion, identify kinetic energy as the energy source, and list factors that affect its rate.

1. Do‑now (5') – Quick quiz on concentration gradients and previous diffusion examples.
2. Mini‑lecture (10') – Define diffusion, present the kinetic‑energy equation (KE = ½ mv²), and emphasise that no ATP is required.
3. Demonstration (10') – Drop coloured beads into warm and cool water; observe and time the spread to illustrate temperature’s effect on kinetic energy.
4. Paired activity (10') – Complete a table of factors (temperature, particle size, gradient, medium, surface area) and predict their impact on diffusion rate.
5. Guided practice (8') – Work through the self‑check questions, discussing answers as a class.
6. Summary & exit ticket (7') – Each student writes one sentence explaining why diffusion is passive and gives a real‑life example; collect for assessment.

Recap that diffusion is driven by the kinetic energy inherent in molecules and ions and that temperature amplifies this energy. Collect the exit tickets as a formative check and assign a short homework: research how diffusion operates in plant leaf stomata and prepare a one‑paragraph explanation.