Lesson Plan

• Describe the process of osmosis and its direction relative to solute concentration.
• Explain how isotonic, hypertonic, and hypotonic solutions affect cell shape.
• Identify the main factors that influence the rate of osmosis.
• Predict the outcome for cells placed in different osmotic environments.
• Apply the concept of osmosis to real‑world biological examples such as plant turgor and kidney function.

• Projector and screen
• Whiteboard and markers
• Printed worksheets with diagrams and tables
• Osmosis demonstration kit (dialysis tubing, isotonic/hypertonic/hypotonic solutions)
• Handout summarising key concepts
• Interactive quiz platform (e.g., Kahoot)

Begin with a short video clip showing plant cells swelling and animal cells shrinking in different solutions to spark curiosity. Ask students what they already know about water movement in cells and set the success criteria: they will be able to state the direction of water movement by osmosis and describe its effects on cell shape.

1. Do‑now (5') – Quick written response to the question: “What happens to a cell when placed in pure water?”
2. Mini‑lecture (10') – Define osmosis, semi‑permeable membrane, and concentration gradient using a projected diagram.
3. Guided inquiry (12') – In groups, students use the osmosis kit to observe red blood cells (dialysis tubing) in isotonic, hypertonic, and hypotonic solutions and record observations.
4. Whole‑class discussion (8') – Compare results, link observations to cell shape changes, and reinforce the key definition.
5. Factors analysis activity (10') – Complete a table identifying how concentration gradient, temperature, surface area, and membrane permeability affect the rate of osmosis.
6. Check for understanding (5') – Exit‑ticket: write one sentence describing what happens to a cell in a hypotonic solution.

Recap the definition of osmosis and the three solution types, highlighting how each influences cell volume. Collect exit‑tickets to gauge understanding and assign a short homework worksheet where students predict cell responses to new solution scenarios.