Science · Colouring and tick-the-box worksheet
Microorganisms Worksheet: Helpful and Harmful Microbes (Free KS2)
Microorganisms are living things that are far too small to see without a microscope, yet they shape the world around us every day. This free printable worksheet introduces the broad group of microbes that Year 6 children meet in Science, including bacteria, fungi such as yeast and mould, and viruses, and helps them recognise that some are helpful while others can be harmful.
Designed to print neatly onto one A4 page, the sheet combines a colouring task with a sorting activity. It works well as a lesson starter, a homework task, or a calm follow-up to a practical investigation into mould or bread-making.
Helpful and Harmful Microbes
Free Science worksheet · Ages 10 to 11
Activity 1
Colour the four microorganisms. Make the helpful microbes (the bacterium and the yeast) green, and the harmful ones (the mould spot and the virus) red.
- Colour the round bacterium and its wiggly tail green.
- Colour the budding yeast cell green.
- Colour the fuzzy mould spot red.
- Colour the spiky virus shape red.
Activity 2
Read each sentence about microbes. Tick the box only if the sentence describes a HELPFUL microbe.
- Yeast makes bread rise when we bake.
- Some bacteria turn milk into yoghurt and cheese.
- Mould can spoil bread and fruit so we cannot eat it.
- Microbes in the soil break down dead leaves and recycle nutrients.
- Some bacteria can cause food poisoning if food is not stored safely.
- A virus can give us a cold or the flu.
Helpful and Harmful Microbesowee.worldAnswer key
- Yeast makes bread rise when we bake. — tick
- Some bacteria turn milk into yoghurt and cheese. — tick
- Microbes in the soil break down dead leaves and recycle nutrients. — tick
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 cannot reproduce on their own, so the curriculum focus is really on bacteria and fungi. This worksheet still includes a virus shape because children encounter the word so often, but the discussion can centre on living microbes.
Helpful microbes children already know
Many microbes are genuinely 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, some fungi produce the mould that grows on old bread or fruit, 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; the central message of the topic is that microbes are a mixed group, and most 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 gives children time to look closely at the different shapes, 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).
Frequently asked questions
What is a microorganism for KS2?
For KS2, a microorganism is a living thing that is too small to see without a microscope. The main examples children learn are bacteria, fungi (such as yeast and mould) and viruses, and the key idea is that microbes form one of the broad groups of living things alongside plants and animals.
Are microorganisms taught in Year 5 or Year 6?
Microorganisms appear in the Year 6 'Living things and their habitats' unit, where children classify living things into broad groups including microorganisms, plants and animals. This worksheet is pitched at ages 10 to 11 but can be used for revision in Year 5 too.
What are some helpful and harmful microorganisms?
Helpful microbes include yeast (which makes bread rise), the bacteria used to make yoghurt and cheese, and microbes that break down dead material in soil. Harmful microbes include bacteria that cause food poisoning, mould that spoils food, and viruses that cause colds and flu.
Is a virus a living thing?
Scientists do not fully agree. A virus cannot grow or reproduce on its own, so many consider it not truly alive. For this reason the curriculum focuses mainly on bacteria and fungi as living microorganisms, though the word virus is included here because children meet it so often.
Is this microorganisms worksheet free to print?
Yes. This worksheet is completely free to download and print. It fits onto one A4 page and combines a colouring task with a tick-the-box sorting activity, making it ready to use at home or in the classroom.
Curriculum links
- Year 6 Science, Living things and their habitats: describe how living things are classified into broad groups according to common observable characteristics and based on similarities and differences, including microorganisms, plants and animals.
- Year 6 Science, Living things and their habitats: give reasons for classifying plants and animals based on specific characteristics.
- Working scientifically (Years 5 and 6): recording data and results using scientific diagrams and labels, and reporting findings from enquiries.
- Working scientifically (Years 5 and 6): using straightforward scientific evidence to answer questions or to support their findings.
Made by The Owee education team. Updated 02/06/2026. Free to print and share.
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