| Lesson Plan |
| Grade: |
Date: 25/02/2026 |
| Subject: Biology |
| Lesson Topic: investigate simple diffusion and osmosis using plant tissue and non-living materials, including dialysis (Visking) tubing and agar |
Learning Objective/s:
- Describe the principles of simple diffusion and osmosis and the role of semi‑permeable membranes.
- Predict how concentration gradients, temperature and membrane surface area affect the rate of diffusion and osmosis.
- Conduct and analyse experiments using dialysis tubing, agar and potato tissue to quantify water movement.
|
Materials Needed:
- Dialysis (Visking) tubing (5 cm) and agar slabs (1 cm × 5 cm)
- Fresh potato strips (1 cm × 1 cm × 2 cm)
- Sucrose solutions (0 %, 5 %, 10 %, 15 % w/v) and distilled water
- Beakers (250 mL), balances (±0.01 g), timers, thermometers
- Safety goggles and gloves
- Data‑recording worksheets and graph paper
|
Introduction:
Begin with a quick demonstration of a coloured drop diffusing in water to spark curiosity about how substances move. Review prior knowledge of concentration gradients and passive transport. Explain that today’s success criteria are to correctly set up diffusion and osmosis experiments, record data, and interpret results in terms of water potential.
|
Lesson Structure:
- Do‑now (5’) – Students answer a short question on diffusion vs osmosis on the board.
- Mini‑lecture (10’) – Review key concepts, equations, and influencing factors.
- Demonstration (5’) – Show dye diffusion in agar and water movement in dialysis tubing.
- Practical Part A – Simple diffusion (dialysis tubing) (15’) – Set up tubes, record initial masses, start timer.
- Practical Part B – Osmosis (potato strips) (15’) – Weigh strips, place in sucrose solutions, monitor temperature.
- Data analysis & discussion (10’) – Calculate mass changes, plot results, relate trends to theory, answer guided questions.
|
Conclusion:
Summarise how the observed mass changes confirm the predicted direction of diffusion and osmosis. Students complete an exit ticket stating one factor that influences each process and propose a simple follow‑up experiment. Assign homework to read a short article on real‑world applications of osmosis.
|