• Quick retrieval from earlier learning (Diffusion, osmosis or active transport?). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which process is this: a raisin swelling in water? (diffusion / osmosis / active transport) → osmosisPrompt: Is it water specifically? Is it going against the gradient?
2. Glucose is absorbed from the small intestine even when the blood already holds more glucose than the gut. How? (it cannot be absorbed / by diffusion down the gradient / by active transport, using energy from respiration / by osmosis) → by active transport, using energy from respirationPrompt: The glucose is moving against its gradient.
3. Transport in cells: which statement is true? (Osmosis needs energy from respiration. / Water moves by osmosis from a concentrated to a dilute solution. / Active transport can move substances from a low to a high concentration. / Active transport only happens in plants.) → Active transport can move substances from a low to a high concentration.Prompt: Which process needs energy?

• Show a microscope image of cells and ask what students think they are looking at.
• Share the objective: Membrane structure, protein channels and bulk transport. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: Is this passive or active transport: a gland cell releasing hormone in vesicles (exocytosis)?
• Step 1: Active transport and bulk transport use energy from ATP.
• Step 2: So the answer is: active (uses ATP)
• Answer: active (uses ATP)
• Pause after each step and ask a student to say what comes next.

• Do these together. Students try each step on whiteboards before you reveal it.
• Use the hints as prompts rather than giving the answer.

1. Is this passive or active transport: facilitated diffusion of glucose through a channel or carrier protein? (passive (no ATP needed) / active (uses ATP)) → passive (no ATP needed)Prompt: Does it go down a gradient by itself?
2. Cystic fibrosis is caused by a faulty chloride ion channel protein. What does this show? (Channel proteins carry oxygen / Ions cross membranes without help / Membrane proteins are vital for moving specific ions across membranes / Phospholipids are made of chloride) → Membrane proteins are vital for moving specific ions across membranesPrompt: Charged ions cannot pass through the fatty middle of the bilayer.

• Students work on the student sheet. Circulate and check the first two answers of every student early.
• Students who finish: write a question of their own for a partner, with the answer.

The 6 questions are on the student sheet below, with answers in the key.

• Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.

1. Is this passive or active transport: osmosis through aquaporin channels? (passive (no ATP needed) / active (uses ATP)) → passive (no ATP needed)Prompt: Does it go down a gradient by itself?
2. Why can oxygen cross the membrane easily but glucose needs a protein? (Glucose dissolves in fat / Oxygen is too big for proteins / Glucose is a gas / Oxygen is small and non-polar; glucose is larger and polar) → Oxygen is small and non-polar; glucose is larger and polarPrompt: The middle of the bilayer is made of fatty tails.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-12.