KS2 Look at how familiar illnesses such as the common cold, diarrhoea, food poisoning and impetigo are spread. Link prevention to personal hygiene: how would pupils get others to wash their hands after going to the toilet, and before meals or cooking, as well as trap germs in handkerchiefs.
KS3 Compare the structure and life history of a bacterium and a virus. Get the students to research the types of organism that cause diseases like the common cold, flu, measles, mumps, polio, meningitis. Find out about the discovery of antibiotics and the way they work. Most standard texts mention the work of Fleming, but consider Salk, Florey and Chain as well.
Investigate the effect of household "antibacterial cleaners" on the growth of bacteria impregnated into agar jelly (observe all safety precautions).