For parents and teachers

What this is for, what it refuses to do, and how to get more out of it than screen time.

Answers are free now. Judgement is not.

Any explanation your child needs — why a fuse blows, how a cooker builds pressure — is one question away, and a machine will answer it better every year. What no machine can do for your child is notice that something is wrong.

Spotting the missing part, the piece that does not belong, the step in the wrong order — that is what engineers, doctors, mechanics and careful adults do all day.

School rarely teaches it, because it cannot be memorised or marked with an answer key. It is built only by meeting broken systems again and again, guessing, being wrong safely, and finding out why. That is the whole design of this app.

How a case works

1. A small, real system is described — a fan, a compost bin, a crowded bus door.
2. Something is wrong with it. Your child works out what.
3. They can press Run with snag and watch the consequence unfold. This is the emotional core: feeling the failure before anyone explains it.
4. When they get it right, their star lights up in its constellation, and a technical note gives the real mechanism and the transferable lesson — with a question to take home to a grown-up.

The note appears the moment the case is solved. We removed a step that used to make children type an explanation first — the note is the teaching, and it should never be rationed.

What your child collects

Every case solved for the first time gives one star — a real one, named for a star that is actually up there, with the colour it really is, how far away it really sits, and one true thing about it. The stars gather in a sky book that belongs to that child alone, and many of them fill real constellations, drawn where the stars truly sit; the last star of one draws the whole pattern, and the app says plainly that it is a good place to stop.

Along the way come badges — a Sky Cup for each finished chapter of the sky book, star medals as the count grows, and a skill badge for each kind of case, from first aid to machines — and stars dress their detective in new outfits. Skills also fill a kit box with real tools, such as a first-aid kit, a spirit level and a tyre pump; each one remembers the case that earned it, and the detective can carry any one of them. All of it is earned and only earned: there is nothing to buy, no coins, no timers, no way for money to make it arrive faster, and nothing is ever taken away.

What you can see

Open Your child's journey in the app's grown-ups' corner: how your child thinks (which of the four kinds of fault they have practised), what they have learned about — safety, kindness, science, nature, machines and more — and three questions to ask them tonight from their latest cases. It is worked out on the phone and sent nowhere, and it shows no scores, no time spent and no ranking against anyone.

Why this, and not one of the thousand others

• Your child breaks it on purpose. Most apps ask for the right answer. Here they decide what they think is wrong, run it, and watch the consequence play out. Being wrong is safe, and it is where the learning actually happens.
• One method, four faults. Something missing, something wrong, something extra, the right steps in the wrong order. Once a child can tell them apart, the same method works on a bicycle, a recipe, a rumour, and a message someone forwarded.
• The explanation is a real mechanism, not a "well done" — written to be understood by a child and still be true.
• Your child teaches it back to you. Every case ends with a "Let's ask grown-ups" question — one your child can now answer and you may not. Or swap places: "Challenge a grown-up" hands you the same case, with no hints, and once you crack it your child explains why before you check the note together. Nothing is scored; the conversation is the point.
• They can build one themselves. Making a mystery for somebody else to solve is the hardest test of understanding there is, and it is part of the app rather than an extra.
• Nothing here is built to keep them. No streaks, no daily rewards, no timers, no leaderboards, and the app cannot send notifications — it never asked for permission to. There is a suggested case each day, but nothing counts days in a row, and skipping it costs nothing. A child who has had enough can put it down and lose nothing.

What we collect: nothing

Progress lives on your device. If you change phones, there is a backup you copy yourself — no cloud involved. Full privacy policy.

Money, and where it hides

Sixty-three of the ninety-nine cases are free, and that includes every case about road safety, first aid, kindness, money sense and staying safe online. The paid packs go deeper into hands-on topics such as machines, camping and kitchen science, and each is a one-time purchase.

Purchases sit behind a grown-up gate: a child can see a pack, but only a grown-up can buy it. The strongest protection is not in our app though — it is in the Play Store itself: turn on "Require authentication for purchases" in your Play settings, which covers every app on the phone.

Getting more than screen time out of it

• Ask the question at the end. Every case ends with "Let's ask grown-ups" — ask it at dinner and let them explain. Your child's journey lists the latest three for you.
• Take the challenge. Let them hand you a case they have already solved. Being the one who is stuck, while they explain, is half the fun.
• Find the same fault in the house. The fridge pushed against the wall, the tap that drips, the bin that smells.
• Let them be wrong. The app is designed so being wrong costs nothing. Try to match that at the table.
• Use the Create tab. Building a mystery for someone else is a harder, better exercise than solving one.

Under six?

We do not make screen content for children under school age, and we explain exactly why — read the birth-to-five guide. What we offer for this age is on paper instead, which is what the evidence actually supports. All of it is free:

• High-contrast baby cards — shapes, nature, animals and birds, downloaded one card at a time. From birth, once they will hold a gaze.
• High-contrast patterns for newborns — stripes, checks and spirals rather than pictures, for the first six months.
• Spot the Snag, for ages 3–5 — find-the-fault cards a child who cannot yet read finds the gap in, and then draws back in with a pencil.

What it is all for

One thing: a child who notices. Not one who looks an answer up faster — that race is already over, and machines won it — but one who senses that something is off, asks why, and keeps asking until the mechanism makes sense. That habit outlasts every syllabus, and it is the whole reason this exists.

Open the app · Using it in a school?