Microorganisms Worksheet: Helpful and Harmful Microbes (Free KS2)

What are microorganisms?

Microorganisms (often shortened to microbes) are living things so small that they can only be seen with a microscope. In the Year 6 classification topic, children learn that microbes form one of the broad groups of living things alongside plants and animals. The most commonly studied examples are bacteria, fungi such as yeast and mould, and viruses. It is worth knowing that scientists do not all agree that viruses are truly alive, because they can only make copies of themselves inside another living cell. The curriculum names micro-organisms as a broad group without listing them, so bacteria and fungi are the clearest living examples. This worksheet still includes a virus because children meet the word so often.

Helpful microbes children already know

Many microbes are useful, and pointing to familiar examples helps the idea stick. Yeast is a fungus that makes bread rise and is used in baking; bacteria are used to turn milk into yoghurt and cheese; and microbes in the soil break down dead leaves to recycle nutrients. Inside our own bodies, friendly bacteria in the gut help us digest food. Linking microbes to everyday objects in the kitchen makes an abstract topic concrete and gives children a reason to value organisms they will never see directly.

Harmful microbes and staying healthy

Some microbes can cause illness or spoil food. Certain bacteria cause food poisoning, moulds (a kind of fungus) grow on old bread or fruit and spoil it, and viruses cause infections such as colds and flu. This is a natural moment to reinforce sensible hygiene: washing hands, keeping food covered and refrigerated, and covering coughs and sneezes. Take care to avoid giving the impression that all microbes are dangerous, or that one kind is always good and another always bad. The same group can do both: some bacteria make yoghurt while others cause food poisoning, and one mould spoils bread while another gave us the antibiotic penicillin. Most microbes are harmless or helpful.

How to use this worksheet at home or school

Begin by talking through the four microbes on the sheet and what makes each one part of the microorganism group. The colouring task asks children to match each microbe to a clue about its shape (a tail, a bud, branching threads, spikes), which is the same kind of observable feature scientists use to classify living things, while the tick activity asks them to decide whether each statement describes a helpful or a harmful microbe. For an extension, ask children to add their own example of a helpful and a harmful microbe, or pair the sheet with a simple observation of mould growing on a slice of bread sealed in a bag (handled by an adult and never opened).

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