• Quick retrieval from earlier learning (Nervous system, reflexes and hormones). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Compared with nerves, hormones usually act… (more slowly but for longer / only in the brain / exactly the same way / faster and for a shorter time) → more slowly but for longerPrompt: Blood travels more slowly than an electrical impulse.
2. Coordination and control: which statement is true? (Reflex actions are controlled by conscious thought. / Homeostasis keeps conditions inside the body steady. / Hormones travel along nerves. / Insulin raises blood glucose.) → Homeostasis keeps conditions inside the body steady.Prompt: Nerves carry electrical impulses; hormones are chemicals.
3. Why are reflexes useful? (They only happen when we sleep / They are fast and automatic, protecting the body from harm / They are slow and careful / They let us think carefully first) → They are fast and automatic, protecting the body from harmPrompt: The message does not have to go to the conscious brain.

• Ask everyone to find their pulse, then jump for 30 seconds and find it again.
• Share the objective: Homeostasis and negative feedback loops. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: In a control system, what role do these play: a gland releasing a hormone?
• Step 1: Effectors (muscles or glands) carry out the response.
• Step 2: So the answer is: effector
• Answer: effector
• 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. In a control system, what role do these play: light-sensitive cells in the retina? (receptor / coordination centre / effector) → receptorPrompt: Detect → decide → respond.
2. Why is it important to keep internal conditions within narrow limits? (Enzymes and cells only work well in a narrow range of conditions / So that we never feel hungry / So that hair grows faster / It is not important) → Enzymes and cells only work well in a narrow range of conditionsPrompt: What happens to enzymes at the wrong temperature or pH?

• 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. In a control system, what role do these play: temperature receptors in the skin? (receptor / coordination centre / effector) → receptorPrompt: Detect → decide → respond.
2. What is negative feedback? (Bad news from a doctor / A change triggers a response that makes the change bigger / A change triggers a response that reverses the change, back towards the set point / A response that never stops) → A change triggers a response that reverses the change, back towards the set pointPrompt: Think of a thermostat in a house.

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-10.