The shape of the lesson
By the end of the lesson, learners can
- Active or passive, natural or artificial: Click each of the four immunity chips and read what gives the protection.
- What is in a vaccine: Every vaccine works the same way: it shows the immune system the antigens of a pathogen without letting the pathogen cause disease.
- Vaccinating a population: One vaccinated person is protected; a vaccinated population stops the pathogen spreading at all.
- Active: you made them, memory cells, long-term.
- Passive: given to you, no memory cells, short-term.
- Natural = everyday life; artificial = medical intervention.
- Vaccine = antigens; herd immunity = enough people immune to stop spread.
One picture every idea returns to
Active immunity develops when your own lymphocytes respond to an antigen, making plasma cells, antibodies and memory cells: it takes time but is long-lasting. Passive immunity is gained when antibodies made by another organism are received: it is immediate but short-lived, because the antibodies are broken down and no memory cells form. Immunity is natural when it comes from normal life (an infection, antibodies across the placenta or in breast milk) and artificial when it comes from medical intervention (a vaccine, an injection of antibodies). A vaccine contains antigens, as dead or weakened pathogens, toxoids, purified proteins or mRNA, that stimulate a primary response and memory cells without causing disease, giving long-term immunity. Vaccination programmes control the spread of disease because when a high proportion of people are immune, the pathogen rarely reaches a susceptible person: herd immunity protects even those who cannot be vaccinated.
Forty-five minutes, phase by phase
| Time | Phase | What happens in the room | Grouping |
|---|---|---|---|
| 0 to 5 min | Hook: predict | Open with the question in the title, Immunity without the illness.. A baby is protected by its mother's antibodies for a few months; a vaccinated adult may be protected for life. Put the figure on the board: it is the one picture every idea in the lesson returns to. | Whole class, then pairs |
| 5 to 13 min | Teach and check: Active or passive, natural or artificial | Click each of the four immunity chips and read what gives the protection. Project tab 7 of the lab (Immunity lab, types of immunity and vaccination) and let a student drive it while the class predicts. | Whole class, then pairs |
| 13 to 21 min | Teach and check: What is in a vaccine | Every vaccine works the same way: it shows the immune system the antigens of a pathogen without letting the pathogen cause disease. | Pairs |
| 21 to 30 min | Teach and check: Vaccinating a population | One vaccinated person is protected; a vaccinated population stops the pathogen spreading at all. | Jigsaw |
| 30 to 36 min | Check | The four Stage 1 questions from the student lesson, answered on mini whiteboards or by show of fingers. Re-teach the one most get wrong. | Individual, then whole class |
| 36 to 43 min | Plenary | The exam-style questions from Stage 2, one at a time: thirty seconds alone, then a random call. The feedback lines in the key give the examiner's wording. | Individual, random call |
| 43 to 45 min | Exit and homework | Set the worksheet below (6 questions, 18 marks). Learners self-assess against the objectives before they leave. | Individual |
Protect the parts that carry the learning
The sequence carries about fifty minutes of material, so the lab is driven by one student while the class predicts rather than explored freely. Times are a guide.
Protected: the check at 30 minutes. It is the only individual read on whether the key idea landed, and it is not cut.
Cut first if the build overruns: the last check in Vaccinating a population, never the check or the plenary.
In a 60 minute block: run worksheet questions 1 to 3 in class as a Rally Coach set and model both the hardest worked example and its check live.
Jigsaw
Split the content into expert pieces. Expert groups master one piece each, then regroup so every home team has one expert per piece, and each expert teaches their piece to the team.
The full structure, with its variations and the other twelve, is on the cooperative-learning page.
What to head off, and how
| Trap learners fall into | Teaching move that pre-empts it |
|---|---|
| Passive immunity is short-lived because no memory cells are made, not because the antibodies are "weaker". | Always mention memory cells when you compare active and passive immunity. |
| Herd immunity does not mean every person is immune. | It means enough people are immune that the pathogen cannot keep spreading. |
Vaccination and types of immunity: worksheet
6 questions, 18 marks. Written in the style of the papers; no past paper question is reproduced.
Describe the differences between active immunity and passive immunity.
Give one example each of passive natural immunity and active artificial immunity.
Explain how a vaccine provides long-term immunity to a disease.
In a model town of 225 people, 80% are vaccinated and immune. Calculate how many people are still susceptible to the disease.
Explain how a mass vaccination programme can control the spread of an infectious disease, even though not everyone in the population is vaccinated.
Suggest why it has been difficult to develop vaccines against some diseases, such as influenza and malaria.
Answer key and marking notes
- Active: antibodies made by the person's own plasma cells after exposure to an antigen; passive: antibodies made by another organism and received.
- Active: memory cells are made; passive: no memory cells.
- Active: takes time to develop; passive: immediate.
- Active: long-lasting; passive: short-lived because the antibodies are broken down.
- Passive natural: antibodies crossing the placenta from mother to fetus, or in breast milk.
- Active artificial: vaccination.
- The vaccine contains antigens (for example from a dead or weakened pathogen) that cannot cause the disease.
- The antigens stimulate a primary response: T-helper and B cells with complementary receptors are selected and cloned.
- Plasma cells make antibodies and memory cells are formed.
- Memory cells remain for years and give a rapid secondary response if the real pathogen enters.
- Number vaccinated = 0.80 × 225 = 180.
- Susceptible = 225 − 180 = 45 people.
- Vaccinated people are immune, so they do not become infected and do not pass the pathogen on.
- When a high proportion is immune, an infected person is unlikely to contact a susceptible person, so transmission chains break.
- This herd immunity protects people who cannot be vaccinated, such as young babies.
- Influenza shows antigenic variation: its surface antigens change, so memory cells from earlier exposure or vaccines do not recognise new strains.
- The malaria parasite spends much of its life cycle inside body cells (liver and red blood cells), hidden from antibodies.
- Malaria parasites have many antigens that change between stages of the life cycle, so one vaccine does not target all stages.
8 multiple-choice questions on this lesson
From the topic question bank. Assign them in the app for a marked score in your gradebook, or run the topic as a class game.
Which example gives active natural immunity?
- Arecovering from chickenpox
- Breceiving antibodies in breast milk
- Cbeing given a measles vaccine
- Dbeing injected with tetanus antitoxin
Why does passive immunity last only a few weeks or months?
- Athe antibodies received are broken down and no memory cells are made
- Bthe antibodies received are destroyed by the person's own T-killer cells
- Cthe antibodies received only bind to antigens for a few days
- Dpassive immunity stops the person's own lymphocytes from working
Which substance could be the active ingredient of a vaccine?
- Aa toxoid made by inactivating a bacterial toxin
- Bantibodies purified from the blood of a recovered patient
- Can antibiotic that kills the pathogen
- Dmemory cells taken from a vaccinated person
A baby is born to a mother who is immune to measles. Why is the baby not vaccinated against measles until it is several months old?
- Aantibodies from the mother may bind the vaccine antigens before the baby's own immune system responds
- Bthe baby's lymphocytes are already producing measles antibodies
- Cthe baby has inherited memory cells for measles from its mother
- Dmeasles cannot infect babies in their first year
What is meant by herd immunity?
- Awhen enough people in a population are immune that the pathogen cannot spread, protecting those who are not immune
- Bwhen every person in a population has been vaccinated
- Cwhen animals pass on immunity to the humans who look after them
- Dwhen antibodies are shared between people who live together
The graph shows the percentage of children vaccinated against measles (dashed line, right axis) and the number of measles cases (solid line, left axis) in a country during a vaccination programme. Which conclusion is best supported?
- Acases fell as vaccination coverage rose, and fell to very low levels once coverage passed about 80%
- Bthe vaccination programme caused every case of measles to disappear by year 6
- Ccases fell by the same number each year as coverage rose
- Dcoverage rose because the number of cases fell
Use the graph. By what percentage did the number of measles cases fall between year 1 and year 4?
- Aabout 83%
- Babout 17%
- Cabout 500%
- Dabout 56%
Smallpox was eradicated using ring vaccination, but there is still no vaccine that gives long-term protection against malaria. Which difference between the pathogens best explains this?
- Athe smallpox virus had stable antigens, while the malaria parasite changes its antigens and lives inside body cells
- Bsmallpox was caused by a bacterium, which is easier to vaccinate against
- Cmalaria is not an infectious disease, so vaccination cannot control it
- Dsmallpox vaccines contained antibodies, which work for longer than antigens
Quiz key
Recovering from an infection means your own immune system made antibodies and memory cells without medical help: active natural. Antibodies in breast milk are passive natural. A vaccine gives active artificial immunity. An injection of antitoxin is passive artificial.
Received antibodies are proteins that are gradually broken down, and because the person's lymphocytes were not involved, no memory cells or plasma cells exist to replace them. T-killer cells attack infected body cells, not antibodies. Antibodies keep binding for as long as they last. Passive immunity does not switch off the person's own lymphocytes.
Vaccines contain antigens in a harmless form; a toxoid is an inactivated toxin that still carries the toxin's antigens. Purified antibodies would give passive immunity, not a vaccine response. Antibiotics kill bacteria but do not stimulate immunity. Memory cells from another person would be non-self cells and would be destroyed.
Maternal antibodies that crossed the placenta are still present for the first months; they can bind the vaccine antigens and remove them before the baby's own B and T cells are stimulated. The baby has not yet made its own measles antibodies. Memory cells are not passed from mother to baby. Young babies can catch measles once maternal antibodies have gone.
Herd immunity arises when a high proportion is immune, so an infected person rarely contacts a susceptible one and transmission stops; people who cannot be vaccinated benefit. It does not require every person to be vaccinated. It has nothing to do with animals, and antibodies are not shared between people living together.
Cases fell from about 180 to under 5 per 100 000 as coverage rose from about 20% to over 90%, and dropped below about 30 per 100 000 once coverage passed about 80% (years 4 to 6). The graph shows a correlation; cases are low but not zero in year 6. The yearly fall was not equal (40, 60, 50, 20, 6). Coverage is the cause being tested; nothing suggests falling cases increased vaccination.
Year 1 is about 180 and year 4 about 30 cases per 100 000. The fall is 150, and 150 / 180 × 100 = about 83%. 17% is the year 4 value as a percentage of year 1, not the fall. 500% divides the fall by the year 4 value instead of the starting value. 56% uses year 3 (about 80 cases) instead of year 4.
The smallpox virus showed little antigenic variation, so one vaccine protected against all strains and ring vaccination could stop each outbreak; humans were its only host. Plasmodium changes its surface antigens between stages and spends much of its life cycle inside liver cells and red blood cells, out of reach of antibodies. Smallpox is caused by a virus, not a bacterium. Malaria is infectious, transmitted by mosquitoes. Vaccines contain antigens, not antibodies.
What to project
The student lesson embeds these tabs. Open them full screen on the projector; every slider has a drag handle on the stage.
Slides for this lesson
A projectable deck for every pack is on the way. Until then, present the student lesson full screen: its sections, figure and lab tabs follow the same order as the plan above.