• 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. Which hormone lowers blood glucose concentration? (oestrogen (estrogen) / insulin / testosterone / adrenaline (epinephrine)) → insulinPrompt: It is made in the pancreas.
2. Coordination and control: which statement is true? (Hormones travel along nerves. / Insulin raises blood glucose. / Normal human body temperature is about 37 °C. / Reflex actions are controlled by conscious thought.) → Normal human body temperature is about 37 °C.Prompt: Nerves carry electrical impulses; hormones are chemicals.
3. Compared with nerves, hormones usually act… (more slowly but for longer / only in the brain / faster and for a shorter time / exactly the same way) → more slowly but for longerPrompt: Blood travels more slowly than an electrical impulse.

• 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? (So that hair grows faster / So that we never feel hungry / Enzymes and cells only work well in a narrow range of conditions / 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. Homeostasis: which statement is NOT true? (Body temperature is kept close to 37 °C. / Negative feedback makes changes bigger. / In negative feedback, a rise in a value triggers changes that lower it. / Effectors can be muscles or glands.) → Negative feedback makes changes bigger.Prompt: Which part detects and which part responds?
2. Why is it important to keep internal conditions within narrow limits? (So that we never feel hungry / Enzymes and cells only work well in a narrow range of conditions / 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?

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