--- title: "Bread mold experiment: mould in 3 days, then for real" description: "A mold experiment for kids: watch mould bloom in 3 days on screen, then grow bread mould for real in a sealed bag. What grows where, salt, and is it dangerous?" source_name: "Game Tailors" source_url: "https://extreemtekenen.nl/en/experiments/mold-in-3-days/" site_home: "https://extreemtekenen.nl/" source_description: "The drawing app where the paper is real. No ads, no accounts, no data collected." locale: "en" legal: - "Game Tailors · Schieweg 15Y-40, 2627 AN Delft (NL)" - "KvK 92437702 · VAT NL866044474B01" - "info@gametailors.com · +31 6 4227 5919" copyright: "© 2026 Game Tailors" published_at: "2026-10-24T00:38:52.564Z" modified_at: "2026-10-24T05:05:03.065Z" --- # Bread mold experiment: mould in 3 days, then for real ## Three days in one tap: watch the fuzz move in Mould is a living thing that grows on food. Its spores float in the air everywhere, and when one lands on damp food it sends out threads and, after a day or two, a fuzzy spot appears. Warmth and damp speed it up; salt, vinegar, freezing and baking hold it back. [Play in your browser]()[Do it for real](<#for-real>) - Ages 5\+ - 3 days on screen, 1–2 weeks for real - The bag stays shut ![Painted illustration of the painter peering through a magnifying glass at bread and a strawberry with fuzzy mould spots, beside a calendar with three days crossed off.]() ## Quick facts Age 5 to 10 Time One tap on screen; 1 to 2 weeks for real, a minute a day to look Mess None, if the bags stay sealed Adult needed To set it up and to throw the bags away, unopened You need Bread, zip-lock bags, sticky tape, a marker \(almost free\) On screen / for real Both ## Mould in Extreme Drawing Put some food on the paper: a squeeze of ketchup, a scoop of ice cream, a few banana or tomato slices, a slice of cheese or a puddle of milk \(all in the free **Kitchen** and **Science** tabs\). Then open the **Time** tab and tap **Wait 3 days**. The sun and moon race across the sky, and when the days are up, mould colonies have bloomed on the food in four kinds: blue-green, white fuzz, black spots and orange. It follows the same rules as real mould: - **It only grows where there's food.** Bare paper, paint and crayon get at most a faint halo. - **Damp helps.** Food on wet paper goes mouldy faster. - **It takes time.** Like real mould, it takes about a day to show, so a Wait 1 hour shows nothing yet. - **Salt stops it.** Shake **Salt** from the Sieve onto one blob of food and leave another bare: the salted one stays clean for weeks. - **Vinegar kills it.** Drip **Vinegar** on a colony and the fuzz dies into a flat, darker stain. **Bleach** drops kill it and wipe the stain away. **Bake in the oven** kills it too; the **freezer** only pauses it. Close the app and come back days later: the page has aged too. [Play in your browser]() ![Painted illustration of the painter sniffing a lemon behind a counter with ketchup, mustard, honey, an egg, oil, butter, flour, salt, sprinkles and a rolling pin.]() ## The bread mould experiment, in sealed bags **You need** - Three slices of the same bread \(bakery bread goes mouldy faster than packaged bread with preservatives\) - Three zip-lock bags and sticky tape - A permanent marker - A few drops of water, and a little vinegar for slice three - A notebook for drawings, or a phone to take a photo through the bag each day **Important:** once a bag is sealed, it is **never opened again**. At the end it goes into the bin still closed. 1. Label three bagsWrite on them: **dry**, **damp** and **vinegar**, plus today's date. 2. Prepare the slicesSlice one stays as it is. Sprinkle slice two with a few drops of water. Brush slice three with a little vinegar. 3. Seal them upAn adult slides each slice into its bag, presses out most of the air, zips it shut and tapes over the seal. 4. PredictWhich slice will go mouldy first? Which last? Write your guess down before you put the bags away. 5. Keep them warm and darkPut the bags side by side in a warm cupboard, away from food you're going to eat. 6. Look every day, through the bagDraw or photograph what you see. Count the spots and note the colours: white fuzz, blue-green, black dots. 7. Throw them away, still sealedAfter one or two weeks, an adult puts the closed bags straight in the outside bin. Wash hands after handling them. Safety Never open the bags, sniff them or touch the mould: spores can make people sneeze, wheeze or feel unwell. If anyone in the family has asthma or a mould allergy, do this one on screen only. Keep the bags away from food, and away from small children who might open them. ## Is mould dangerous? Some moulds are useful: they make the blue in blue cheese and the medicine penicillin. Others make poisons, and their spores can set off allergies and asthma. You can't tell which is which by looking, so treat all mould on food as *look, don't touch*. **What if you eat a bit by accident?** Most people are fine after a bite of mouldy bread. Don't eat any more, though, and throw the rest of the loaf away: the fuzz you see is only the top of the mould, and its threads reach further into soft food than you can see. If someone feels unwell afterwards, call your doctor. ### What grows where - **Bread:** white fuzz that grows black dots \(black bread mould\), and blue-green patches - **Fruit:** grey-green or white fuzz, often starting where the skin is bruised - **Cheese:** blue-green or white spots - **Honey and jam:** hardly ever: they're so sugary that mould can't get the water it needs. In the app, honey doesn't go mouldy either. ### For kids Mould is a tiny living thing that eats food. Its seeds, called spores, fly around in the air, and when one lands on damp food it starts to grow, until you can see a fuzzy spot. ## Why mould grows \(and what stops it\) **For grown-ups.** Moulds are fungi, a kind of micro-organism. They spread by spores so small and light that they're in almost all air. A spore that settles on food with enough water germinates and grows a network of fine threads \(hyphae\) through it, digesting it as it goes. Only when the colony is big enough, usually after a day or two, do you see it, and then it makes new spores, which is the coloured, fuzzy part. Moulds are decomposers: they break dead material down and return it to the soil. They need food, water and a suitable temperature, so anything that removes one of those slows them: salt and sugar pull the water away \(salted fish, jam\), vinegar makes food too acidic, the freezer stops growth without killing it, and cooking kills it. ## Predict, then try next Each of these takes seconds in the app. Guess first, then tap Wait 3 days. ### Salted or not? Two blobs of ketchup, one shaken with salt. Which one goes mouldy? ### Wet paper or dry? Pour some water first and put food on the wet patch and on dry paper. Where does mould come first? ### Honey or ketchup? Squeeze a blob of each \(both are in the Kitchen squeeze bottle\). Only one goes mouldy. Can you work out why? ### Freezer, then wait? Put the page in the freezer, then Wait 3 days. Does the cold kill mould, or only pause it? ## Mould in the classroom Fits KS2 Year 6 *living things and their habitats* \(micro-organisms\) and NGSS 5-LS2-1 \(decomposers in the movement of matter\). The real bread bags need a week or more; the app gives the class a result in the same lesson, so pupils can test salt, damp and cold on the whiteboard while the real bags sit sealed on the windowsill. [Ideas for teachers]() ## Mould questions How long does it take for bread to go mouldy? Fresh bakery bread kept warm and slightly damp often shows mould in three to seven days. Packaged bread with preservatives can take one to two weeks, and bread kept in the fridge or freezer much longer. Why does mould grow faster on damp bread? Mould needs water to grow and to digest its food. A damp slice gives spores everything they need, while a very dry slice slows them right down. Does salt stop mould? A lot of salt does: it pulls out the water that mould needs, which is why salted fish and ham keep. The little salt in ordinary bread only slows it a bit. In the app, salt shaken on food keeps mould away for weeks. What happens if you eat mould? A bite by accident usually does no harm, but some moulds make poisons and spores can trigger allergies, so never eat mouldy food on purpose. Throw the whole loaf away, and call a doctor if someone feels unwell. Is it mold or mould? Both are right. Mold is the American spelling and mould the British one; it's the same fuzzy fungus. ## More living things and time ![Painted illustration of the painter spraying water on cress sprouting in a heart shape on damp kitchen paper, with a seed packet and seeds.]() ### [Growing cress]() Seeds that only sprout while they're damp, and wilt when they dry out. ![Painted illustration of the painter in oven gloves sniffing a golden loaf, with a ball of dough, a rolling pin, a bowl of yeast and a pretzel.]() ### [Bread and yeast]() Yeast is a living fungus too: watch dough rise when it's warm. ![Painted illustration of the painter crouching by an oven, watching a crayon drawing toast golden inside, with an ice-cube tray and a lemon.]() ### [What happens if…]() Short answers to kids' own questions, from freezing paint to leaving food out. ## Skip three days and see what grew Put food on the paper, salt half of it and tap Wait 3 days. Then seal some bread in a bag for the slow, real version. [Play in your browser]()[All experiments]()