• Quick retrieval from earlier learning (Vaccines, antibiotics and painkillers: what each can do). Students answer on mini whiteboards.
• Show answers together and note who needs support in the main task.

1. Which type of medicine is described: penicillin, discovered by Alexander Fleming? (vaccine / antibiotic / painkiller) → antibioticPrompt: Does it prevent, cure a bacterial infection, or only ease symptoms?
2. In one region, measles vaccination coverage rose from 63 % to 95 %. Yearly measles cases fell from 47 to 2. Which conclusion is best supported? (The vaccine made measles cases rise. / Cases fell sharply after vaccination rose, which supports the vaccine reducing measles. / The data prove that measles has disappeared everywhere. / Vaccination has no link with the number of cases.) → Cases fell sharply after vaccination rose, which supports the vaccine reducing measles.Prompt: What happened to cases as coverage increased?
3. Why are patients told to finish the whole course of antibiotics? (To kill all the bacteria so none survive to become resistant / Because antibiotics are vitamins / To use up the packet / To prevent future viral infections) → To kill all the bacteria so none survive to become resistantPrompt: The toughest bacteria are the last to die.

• Ask everyone to find their pulse, then jump for 30 seconds and find it again.
• Share the objective: Antibodies, memory cells and the secondary immune response. Read the success criteria together.

• Work through the example out loud, saying why you do each step, not just what you do.
• Example: After a first infection, a person's antibody level peaked at 25 arbitrary units after 12 days. After a second infection with the same pathogen it peaked at 250 units after 4 days. How many times higher was the second peak?
• Step 1: 250 ÷ 25 = 10
• Step 2: So the answer is: 10
• Answer: 10
• 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. After a first infection, a person's antibody level peaked at 20 arbitrary units after 12 days. After a second infection with the same pathogen it peaked at 400 units after 4 days. How many times higher was the second peak? → 20Prompt: Divide the second peak by the first.
2. Phagocytes are white blood cells that… (clot the blood / carry oxygen / engulf and digest pathogens / make antitoxins only) → engulf and digest pathogensPrompt: "Phago" means eating.

• 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. What are antigens? (a type of bacteria / medicines / molecules on the surface of a pathogen that the immune system recognises / white blood cells) → molecules on the surface of a pathogen that the immune system recognisesPrompt: Antibodies fit these molecules.
2. The immune response: which statement is NOT true? (Antibodies are a type of white blood cell. / Vaccines lead to the formation of memory cells. / Lymphocytes produce antibodies. / Each type of antibody fits one specific antigen.) → Antibodies are a type of white blood cell.Prompt: What kind of molecule is an antibody?

Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-11.