• 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: glucose absorbed from the gut when its level there is low? (diffusion / osmosis / active transport) → active transportPrompt: 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? (by diffusion down the gradient / by osmosis / it cannot be absorbed / by active transport, using energy from respiration) → by active transport, using energy from respirationPrompt: The glucose is moving against its gradient.
3. Transport in cells: which statement is true? (Osmosis is the movement of water molecules. / Osmosis needs energy from respiration. / Active transport only happens in plants. / Water moves by osmosis from a concentrated to a dilute solution.) → Osmosis is the movement of water molecules.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: a gland cell releasing hormone in vesicles (exocytosis)? (passive (no ATP needed) / active (uses ATP)) → active (uses ATP)Prompt: Does it go down a gradient by itself?
2. What are the two parts of a phospholipid molecule? (a hydrophilic (water-loving) head and two hydrophobic (water-fearing) tails / a nucleus and a membrane / two heads and no tails / a protein and a sugar) → a hydrophilic (water-loving) head and two hydrophobic (water-fearing) tailsPrompt: This is why phospholipids form a double layer in water.

• 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 8 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. Membranes: which statement is true? (Facilitated diffusion moves substances against their gradient. / Large proteins pass through the membrane by simple diffusion. / Facilitated diffusion uses carrier or channel proteins but no ATP. / Phospholipid tails are attracted to water.) → Facilitated diffusion uses carrier or channel proteins but no ATP.Prompt: Which processes need ATP?
2. Is this passive or active transport: simple diffusion of oxygen through the phospholipid bilayer? (passive (no ATP needed) / active (uses ATP)) → passive (no ATP needed)Prompt: Does it go down a gradient by itself?

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