---
title: "Drawing app for kids: Professor Oops by Game Tailors"
description: "A drawing app for kids aged 4 to 10 where paint bleeds, ketchup splats and pages bake and freeze. No ads, no accounts, works offline. Free to start."
source_name: "Game Tailors"
source_url: "https://professoroops.com/en/"
site_home: "https://professoroops.com/"
source_description: "The drawing app where the paper is real. No ads. No accounts. No personal data: only anonymous counts, which you can switch off."
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: "2026-10-24T00:39:25.167Z"
modified_at: "2026-10-29T20:56:52.175Z"
---

# Drawing app for kids: Professor Oops by Game Tailors

## Draw a masterpiece. Then squirt ketchup on it.

On this paper, that's allowed: it really reacts. Ketchup soaks in, paint runs and ants come for the crumbs. No ads, no accounts, no personal data, works offline. Free to start.

[Play free in your browser](<https://play.professoroops.com/?lang=en>)[See the experiments](<https://professoroops.com/en/experiments/>)

- No ads
- No accounts
- Works offline

![Painted illustration of Professor Oops, the grey-bearded painter in a red beret, squeezing a ketchup zigzag onto a yellow sheet, with a cracked egg, crayons, a red cabbage and a dish of swirling milk.](<https://professoroops.com/_assets/entity_Ujl2Hf901LPYLeE1N3b3.webp>)

## A drawing app for ages 4 to 10, with no ads, account or wifi

**No ads · No accounts · Works offline · Free to start, one-time €5.99 unlock for grown-ups.** Made by Game Tailors in the Netherlands, on iPhone, iPad, Android and in the web browser.

## You draw. The cat walks right through it.

Start with a crayon drawing, a watercolour or a colouring page. Then open a tab: squirt ketchup on it, bake it in the oven or leave it a week in the sun. Every tool reacts with every other one, because they all work on the same simulated paper.

![Painted illustration of the painter brushing a rainbow watercolour that bleeds into wet paper, with crayons, markers, a paint box and a child's rainbow drawing.](<https://professoroops.com/_assets/entity_qBSwVGLZdXzWCxqVaFu8.webp>)

### Drawing tools

Crayons, coloured pencils, markers, paint and watercolour that bleeds into wet paper. Plus a paint board, stencils, a ruler, a compass and spiral gears.

![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.](<https://professoroops.com/_assets/entity_1YsK8FPihpkCaLK3mThv.webp>)

### [Kitchen](<https://professoroops.com/en/experiments/bread-and-yeast/>)

Ketchup, mustard and honey, eggs, ice cream, chocolate, cooking oil, flour and yeast. Knead dough, let it rise and bake a golden loaf.

![Painted illustration of the painter, goggles on his beret, studying a bottle foaming over in stripes, with red cabbage juice in pink and green glasses and fizzing baking soda.](<https://professoroops.com/_assets/entity_jHv10qUphz6H9VtrjNeG.webp>)

### [Science](<https://professoroops.com/en/experiments/>)

Red cabbage juice, vinegar, baking soda, food colouring, dish soap, milk, secret ink, elephant toothpaste and a cola-and-mints geyser.

![Painted illustration of the painter blowing soap bubbles over a toothpaste stripe, a sponge, soap suds, a spray bottle, cotton buds and a hair dryer.](<https://professoroops.com/_assets/entity_p6xZw2fAJPBzQqlDe5RJ.webp>)

### Bathroom

Water, a sponge and paper towel, bleach drops for the safety lesson, and in the full toolbox soap suds, a spray bottle and a hair dryer.

![Painted illustration of the painter sprinkling glitter on a glue star, beside salt on a glue line soaking up blue paint, stickers, ink droppers, a stencil and tape.](<https://professoroops.com/_assets/entity_dYKxZ9cEMldCwYXE6yd0.webp>)

### [Craft](<https://professoroops.com/en/techniques/>)

Glue and glitter for salt painting, ink drops, and in the full toolbox tape, stickers, stamps, googly eyes and a toothpick for scratch art.

![Painted illustration of the painter watching a line of ants march to a drop of honey through a magnifying glass, with a snail, sprouting cress and a watering can.](<https://professoroops.com/_assets/entity_XCmzGeDgcKJYjPH9Felr.webp>)

### Garden

Ants that come for the crumbs, free from day one. In the full toolbox: mud, sand, leaves, cress seeds that sprout, a pigeon, a puppy, a cat and a snail.

![Painted illustration of the painter pushing a toy car through blue paint, leaving tyre tracks, beside a monster truck, a beach ball, a football and a marble.](<https://professoroops.com/_assets/entity_Ous2FAFeixeVW2G070EG.webp>)

### Toy box

In the full toolbox: toy cars and a monster truck through wet paint, balls, bubbles, a water pistol and slime.

![Painted illustration of the painter studying a splash of blue ink through a magnifying glass, with a hammer, a squashed marker, a scraper, a ruler, an iron and a bank card.](<https://professoroops.com/_assets/entity_XtJsvef0Q729U5BX7qzI.webp>)

### [Toolbox](<https://professoroops.com/en/safety/>)

An iron, a paint bucket, a scraper, a hammer, a magnifying glass and a match. All of it stays safely on the screen.

## See what happens on screen, then find out why in your kitchen

A Time tab skips ahead: wait 3 days and mould grows on the food you left, bake the page and the crayon melts into deep colour, freeze it and wet watercolour grows ice ferns, leave it a week in the sun and the colours fade except under whatever was lying on top.

On this site every experiment has a second half: how to do the safe version in your own kitchen, with an adult, and why it works. The ones that are never safe at home \(bleach with vinegar, water on burning oil\) stay on the screen, and we say so plainly.

[Kitchen science experiments](<https://professoroops.com/en/experiments/>)[Safety lessons](<https://professoroops.com/en/safety/>)

![Painted illustration of two sheets of paper, one covered in frost ferns from the freezer and one baked golden from the oven, the painter holding an ice cube and an oven glove.](<https://professoroops.com/_assets/entity_CZYstgLvxc7WIGkMtEmK.webp>)

## One drop of soap and the milk starts to swirl: experiments to start with

![Painted illustration of the painter touching a dish of milk with a soapy cotton bud while red, blue, yellow and green food colouring swirls outwards.](<https://professoroops.com/_assets/entity_Wxm9on1gCEAEXSwrruSk.webp>)

### [Magic milk](<https://professoroops.com/en/experiments/magic-milk/>)

One drop of dish soap and the food colouring rushes away and swirls.

![Painted illustration of a bottle on a tray pouring out a fat foam snake in pink, yellow, blue and white stripes, the painter in goggles leaning back, amazed.](<https://professoroops.com/_assets/entity_ej2Rc38q0M0xxwnuyzLU.webp>)

### [Elephant toothpaste](<https://professoroops.com/en/experiments/elephant-toothpaste/>)

A warm, stripy snake of foam pushes out of the bottle.

![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.](<https://professoroops.com/_assets/entity_AMqwn3rMfIoTaSoABf4t.webp>)

### [Mould in 3 days](<https://professoroops.com/en/experiments/mold-in-3-days/>)

Leave food on the page, skip three days and see what grows.

![Painted illustration of the painter pouring purple red cabbage juice into a row of glasses that go from pink through purple and blue to green, with a lemon and baking soda.](<https://professoroops.com/_assets/entity_exC6oxdRrs9iFlnv9AWn.webp>)

### [Red cabbage pH indicator](<https://professoroops.com/en/experiments/red-cabbage-ph-indicator/>)

Pink with vinegar, blue-green with baking soda, yellow with bleach.

![Painted illustration of a cola bottle on the grass shooting up a tall fountain of foam as mints drop in, the painter in goggles laughing beside it.](<https://professoroops.com/_assets/entity_f99w6JP3uGUYbLHXEeFM.webp>)

### [Cola and mints](<https://professoroops.com/en/experiments/cola-and-mints/>)

The geyser that rains sticky cola over the drawing.

![Painted illustration of the painter pointing at a golden-brown heart and star that appeared on paper after ironing, with an iron, half a lemon and a cotton bud.](<https://professoroops.com/_assets/entity_4mzzxejuDgjJqpOCZI2L.webp>)

### [Invisible ink](<https://professoroops.com/en/experiments/invisible-ink/>)

Lemon-juice writing that turns brown when you heat it.

![Painted illustration of a parent and child at a kitchen table looking at a colourful painting on a tablet, with a cup of tea, crayons and a ketchup-zigzag drawing.](<https://professoroops.com/_assets/entity_mTeasV5j4te83LcZFkot.webp>)

## Drawing and most experiments free, more tools one purchase, no subscription

No ads, ever. No accounts to make. The app collects no personal data \(only anonymous counts, which you can switch off\), and drawings stay on the device. It works offline, so it's fine in the car or on a plane. Settings sit in a grown-ups area \(**Parents & teachers**\) behind a simple parent gate \(an easy sum\).

It's free to start, with no time limit: all the drawing tools, every time skip and everything in Kitchen, Science and Toolbox. One optional unlock adds the full toolbox, bought once by a grown-up behind the parent gate: **€5.99** in the eurozone \(local prices in each store\), no subscription. Several fingers can draw at once, so two children can share one tablet.

[For parents](<https://professoroops.com/en/for-parents/>)[What it costs](<https://professoroops.com/en/for-parents/one-honest-price/>)

## No ads, no accounts, 28 languages

Not in the app

✕ No ads  
✕ No accounts  
✕ No subscription  
✕ No notifications  
✕ No personal data

*Only anonymous counts, which you can switch off.*

Where, and in which languages

✓ iPhone and iPad  
✓ Android phones and tablets  
✓ In the web browser  
✓ The apps work offline  
✓ 28 languages in the game

What it costs

**Free to start**

✓ €5.99 once for the full version  
✓ Bought by a grown-up, behind a parent gate  
✓ Local prices in each store

*Ages 4 to 10 · Made by Game Tailors, the Netherlands*

## For teachers: kitchen science on the whiteboard, without the mess

Show melting and freezing, acids and alkalis, mould and decay on the whiteboard, let the class predict, then do the safe version for real. No student accounts and no personal data, and the browser version runs without an install.

Our teacher pages map each experiment to topics such as NGSS 2-PS1-4 \(reversible and irreversible changes\) and KS2 Year 5 "properties and changes of materials".

[For teachers](<https://professoroops.com/en/for-teachers/>)[Lesson plan: reversible changes](<https://professoroops.com/en/for-teachers/reversible-changes/>)

![Painted illustration of three children and the painter at a classroom table with red cabbage juice in pink, purple and green glasses and a magnifying glass.](<https://professoroops.com/_assets/entity_CUuRGVMoCwAw1WFLQP0X.webp>)

## Ages, price, offline, safety: questions parents ask

What is Professor Oops?

A drawing and painting app by Game Tailors in which the paper behaves like real paper: paint bleeds and dries, food stains and goes mouldy, and pages can be baked, frozen or left in the sun. It also shows real kitchen science, such as red cabbage juice changing colour. The name belongs to its host, the painter in the red beret you see all over this site.

What ages is it for?

Children of about 4 to 10. Younger children mostly splat, smear and draw; older ones try the experiments and the time skips on purpose.

How much does it cost?

It's free to start, with no time limit. One optional unlock adds the full toolbox: €5.99 in the eurozone \(local prices in each store\), bought once by a grown-up behind a parent gate. No subscription and no ads.

Does it work offline?

Yes. The iPhone, iPad and Android apps work without Wi-Fi or mobile data. The browser version needs a connection to load.

Are the safety lessons right for young children?

Yes. The dangerous things stay on the screen, and the app says why: mixing bleach and vinegar fills the room with chlorine gas and teaches the child to open the window. Our safety pages explain what to do if it happens for real.

## Try it free in your browser, no install

The browser version has the same tools as the apps. Open it, pick up the crayon, and squeeze some ketchup on your drawing.

[Play free in your browser](<https://play.professoroops.com/?lang=en>)[iPhone, iPad and Android](<https://professoroops.com/en/app/>)

- No account
- No ads
- Free to start