Science at key stage 3    (Year 8)

• Use oral questions to establish what pupils know about micro-organisms.
• Provide pupils with stimulus material to explore the range of micro-organisms and their uses or occurrence, eg bread, yoghurt, wine as useful products of micro-organisms, mushrooms and other fungi, large-scale photomicrographs of bacteria and viruses, advertisements for materials which kill household germs, an empty antibiotic bottle. Provide them with additional secondary sources, eg video clips, simulation software providing further information about micro-organisms. Discuss pupils' observations with them and help them construct a table comparing the three kinds of micro-organism.

• Ask pupils what they know about yeast from advertisements they may have seen, eg yeast respiration causing bread dough to rise. Discuss with them how they could investigate how increasing the quantity of sugar affects the quantity of carbon dioxide released, eg by placing a yeast/flour/glucose dough in a measuring cylinder in a warm environment, or by collecting bubbles from a yeast/glucose suspension.
• Help pupils to plan an investigation so that together they obtain sufficient valid and reliable data.

• Establish through questioning the outcomes of the yeast investigation, emphasising that carbon dioxide is produced as yeast respires aerobically and grows. Discuss with pupils ways of growing bacteria, using video clips and illustrations to demonstrate growing bacteria on agar plates, eg in a hospital laboratory.
• Demonstrate how to inoculate a nutrient agar plate, using appropriate aseptic techniques when handling micro-organisms, and help pupils to do this themselves.
• Provide pupils with reference material to find out about growing bacteria or fungi to make a product, eg yoghurt, cheese, Quorn (mycoprotein).

• Ask pupils how colds pass from person to person in a class. Use their answers to explain the term 'infectious' and introduce them to viruses as a form of pathogen.
• Discuss other infectious diseases and how they are transmitted. Provide pupils with reference sources with which to construct a table of methods of transmission, with examples of diseases and causative agents.
• Help pupils to generate a list of ways to avoid infections and then use their ideas to write a leaflet for travellers to a long-haul destination on how to avoid infection by local diseases, eg water-borne intestinal infections, malaria.

• Ask pupils to find out about an example of people preventing the spread of disease when the role of micro-organisms was not known, eg the residents of Eyam in Derbyshire restricting the spread of plague, the work of Dr John Snow identifying wells as the source of cholera infections, the work of Finlay on yellow fever.
• Invite groups of pupils to explain what was done and ask others to evaluate how effective approaches would have been in the light of knowledge about micro-organisms.
• Establish differences between some of the stories, eg John Snow's actions were based on evidence about the distribution of cases of cholera, while the actions of others were not based on observed data. Provide pupils with information about a modern outbreak of a disease, eg Ebola, cholera, E. coli, and ask pupils to identify the range of people involved in containing the spread of infection. Help them to present findings, eg as a poster, flow chart.

• Provide pupils with a range of short questions, testing recall of the main types of micro-organism and their uses, the diseases they cause and how infections are transmitted from person to person. Extend for some pupils by asking questions about the ways in which understanding of infectious diseases has depended on our understanding of micro-organisms.

• Explore pupils' ideas of why people are seldom ill despite surroundings rich in potentially harmful micro-organisms by asking them to complete a concept map using a variety of terms, eg bacteria, virus, hygiene, immunity, vaccination, skin.
• Use pupils' ideas to explain natural barriers to infection, and help pupils to annotate a diagram of the body with natural defence mechanisms. Ask pupils why young children are sometimes less resistant to infections than older children and why breastfeeding can help.
• Use video clips, ICT, slides or illustrations to show the action of white blood cells engulfing micro-organisms. Remind pupils about listening for a specific purpose and thinking about the relevance of the points made. Explain that other white blood cells make matching antibodies that identify and hinder specific microbial activity. Use the presence of antibodies in, eg blood, to link with the previous activity. Point out that all kinds of micro-organisms can cause disease and that each type of micro-organism needs a different set of antibody-making cells. Ask pupils to write a short passage about how blood cells defend against disease.

• Using stimulus material such as video clips, discuss with pupils how infections are treated. Identify prevention of transmission and the action of drugs to kill or suppress micro-organisms, or to relieve symptoms.
• Remind pupils of how to work safely with micro-organisms and help them to investigate the effect of common household anti-microbial compounds, eg toothpaste, anti-perspirant, antiseptics, disinfectants, sterilising solutions, on the growth of bacteria on a nutrient agar plate. Establish that these are not antibiotics but contain agents that can kill bacteria.
• Ask pupils about medicines they cannot buy from the chemist but have to obtain on prescription, and ask them why this is so. Use their answers to explain that antibiotics kill particular bacteria and are not effective against all types of bacteria, eg neomycin sulphate against the bacteria causing middle-ear infection.
• Challenge pupils to explain why:
• people are not prescribed antibiotics when they have a cold or chickenpox
• some bacteria are resistant to antibiotics
• people are always told to complete the course of an antibiotic
• many doctors wish to limit the prescription of antibiotics
• Ask pupils to find out about the initial observation of antibiotic activity by Fleming and the further development by Florey and Chain. Provide them with data about the incidence of diseases that are treatable by antibiotics over the last century and help them to explain trends and patterns.

• Ask pupils about which immunisations they have had, eg polio, DPT (diphtheria/whooping cough/tetanus), MMR (measles/mumps/rubella), HIB (Haemophilus influenzae B), Heaf tests and TB (tuberculosis), and why they had them.
• Explain what is in a vaccine. Show, by using charts, video clips and simulation software, what happens to antibody levels in the blood as the programme of immunisation proceeds. Challenge pupils to predict what happens in the blood when someone re-encounters the micro-organisms against which they have been immunised. Ask pupils to annotate a graph of antibody changes in the blood after, eg DPT, immunisations. Explain that antibodies pass to babies via breast milk and play an important role in protecting newborn babies from disease.

• Provide pupils with secondary data on the incidence of a major childhood disease, eg diphtheria from 1910 to 1955 in a city location. Ask them to relate patterns to the introduction of immunisation and the start of a free health service.
• Ask pupils to find out about programmes of routine immunisations using reference materials, ICT and the internet. Use the information to write a magazine article about the advantages and disadvantages of routine immunisations.

• Ask pupils to produce a concept map of micro-organisms and diseases using the terms in this unit. Using their concept maps they can generate a list of questions to ask each other about micro-organisms.
• Ask pupils to go through the work they have done in this unit and pick out five or six key points, and then in groups agree ten amongst themselves. Compare the lists of different groups and agree a summary of key points with the class, in which closely related points are grouped together.