Professor Oops

How Professor Oops works: what it really simulates

How it works

A drawing app with real science on the page

Every spot on the page keeps track of its own water, colour, heat and what's dissolved in it, and works out what happens next, many times a second. So the same ketchup ends differently, depending on what your child did first.

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Painted illustration of the worktable of Professor Oops, the painter, with sketches pinned up, paint pots, crayons, a sketchbook, a laptop, a ketchup bottle, red cabbage juice and his beret on the chair.

Knead dough and it rises, because the yeast makes gas

Shake flour into a puddle and it drinks the water and turns into dough. Knead it and its gluten builds up. Add yeast and the yeast makes gas, fastest when it's warm, slower with salt in the dough, not at all once it's too hot.

The gluten holds that gas, so the loaf rises. Skip the kneading and the gas gets away. Leave it far too long and the dough sinks back. Nobody animated any of that: it comes from what's in the dough.

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.
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.

Clip a battery to a copper wire and a bulb, and see what the current does

Clip a battery to anything on the page and the current finds its own way, spot by spot, through whatever carries it. Copper wire carries plenty. A pencil line carries a trickle, too little for a bulb. Crayon carries nothing. Salty water carries enough to split the water.

We checked this one against the arithmetic. With a little torch bulb in copper wire, the 1.5 V battery gives 0.27 amps and the 9 V gives 1.23, just what Ohm's law says for that circuit. The 9 V burns the bulb out with a pop.

See why a pan fire gets a lid and never water

Paper catches at about 230 °C. Oil, butter and wax each catch at their own, higher temperature. Water that reaches burning oil turns to steam at once and flings the burning oil up, so on screen you see why a pan fire gets a lid and never water. Wet paper holds a flame back until its water has boiled off.

A lid cuts off the air and the flames go out. Baking soda gives off a gas that does the same. Flour flares up instead, because its fine dust catches as it falls.

Fire stays on the screen.

What to do about a real pan fire
Painted illustration of the painter calmly turning off the hob under a frying pan with its lid on, a damp tea towel beside it.
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.

Leave food out, and mould grows only where it can live

Squeeze out honey and ketchup and tap Wait 3 days. The ketchup goes mouldy (moldy). The honey stays clean, because sugar that thick keeps mould off. Shake plenty of salt on a blob of ketchup and it grows far less.

The page asks the same questions everywhere: is there food, is it damp, how much salt, sugar and acid is there? Disturb a ripe colony and its spores go up into the air, ride the draught, and start new colonies where they land on food.

Wet a black marker dot, and water carries its colours apart

Paper soaks up water by itself, and the water takes along what's in it: acid, salt, sugar, dye. Wet a black marker dot and its dyes travel at different speeds, so it splits into rings of colour. A wash dries with a darker rim. Pencil stays put when you wash over it, because water doesn't move it, and watercolour lifts again.

The air works the same way. It moves over the page as a fluid, pushed by anything going past, and carries smoke, smells and spores. Ants and flies follow those smells.

Painted illustration of paper strips and a coffee filter in glasses of water, where black marker dots have spread into blue, pink and yellow bands, watched by the painter.

Nobody wrote a rule for ants and baking soda

This is the part we care about most. Things don't know about each other: they only meet on the paper. Almost everything leaves something on the page, or reads what's there, by its own properties. So things can work out that we never tried ourselves. Three that we can trace all the way through:

A line of baking soda stops the ants

An ant feels the spot ahead of it. Powder wipes its scent trail, so it loses the way. Flour, cinnamon, vinegar, soap and a puddle stop it too, each for its own reason. There is no list of what stops ants.

Soda on oil puts out the fire, wherever the gas came from

Fizzing soda gives off a heavy gas that lies on the page. The fire only asks how deep that gas is. So soda shaken on the flames does it, and so does vinegar on soda fizzing next to them.

A battery turns cabbage juice pink

Current through salty water leaves acid at one clip and alkali at the other. The cabbage dye reads the acid and goes pink there. Electricity, then chemistry, then colour, with no link written between them.

Where it isn't the real thing

It's a toy, and these are worth spotting together.

  • Time runs fast. Ice cream goes soft in under a minute, a soaked sheet dries in a couple of minutes, and mould that takes days appears in a tap.

  • Falling is slow. Things fall far slower than real gravity, so you can watch the splash.

  • The cabbage colours are looked up. The dye's colours follow charts of the real thing, but the acidity behind them is a rough reading, not a chemistry lab. Lemon juice even fades away as it dries, which real lemon juice doesn't.

  • The oven and the freezer are a shortcut. Twenty minutes at 180 °C is worked out in one go, not played out as heat moving through the page.

  • Sound is not simulated. Things are heard by how loud they are and where, and animals react to that. No sound waves travel.

  • The paper is flat. Air and water are worked out across the sheet, and heights are only piled on top.

The numbers, for the curious

Spots on the page
Up to 512 × 384, each about 0.6 mm
Substances
About 80, from one table of properties
Things dissolved in the paper's water
12
Things the air carries
8

Questions about the simulation

Does everything behave like the real thing?

No. Some of it is worked out step by step, like the current in a wire or yeast in dough. Some of it is a shortcut, like the oven or how fast mould grows. The list above says which.

Can I teach from it?

You can use it to show something and talk about it, and then try the real thing where that's safe. Check anything you rely on against the real thing: the game's numbers are good for some things and rough for others.

Does a phone really run all this?

Yes, on the device, with no internet. A phone uses a coarser page than a big tablet, so everything is a little bigger and simpler there. The game works out how much your device can take.

See it in one experiment

Try something we didn't plan for

Mix two things that have never met and see what the page makes of it. Bread, batteries and burning oil are all in the free part.

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