The cake scale conspiracy
Pip removes the weights from just one side. The scales file a complaint.
x + 3 = 8 ⇒ x = 5Open the case →THE LITTLE PROOF DETECTIVE AGENCY
Pick a “why?”
Bring a snack.
Eight new cases, from what an equation means to why Pythagoras works. No Lean or university mathematics required. Definitions first, then illustrated scenes and a moving diagram linked to each proof step.
A clear route, one story at a time.
Begin with the cake scale. If you have a saved place, continue from there.
Read the first story →- 1. The cake scale conspiracy
- 2. The bakery with missing buns
- 3. The debt-eating pigeon
- 4. The missing two cake strips
- 5. The vanishing corridor
- 6. The triangle that lost a corner
- 7. Four triangles and one vacancy
- 8. The pigeon who built a square staircase
Records stay in this browser. Reading a story and explaining its reason are reflected on separately.
Choose a different story
What feels right today?
These are invitations, not a placement test. Every case stays available; you can change your mind.
New here? Start with The cake scale conspiracy. Like pictures? Try The triangle that lost a corner.
The bakery with missing buns
Three picnic bags, one bun per bag. Why does Pip’s invoice list only one bun?
a(b + c) = ab + acOpen the case →The debt-eating pigeon
Erasing a debt feels like a bonus. But feelings are not yet a proof.
(−a)(−b) = abOpen the case →The missing two cake strips
Pip bought a bigger square cake. Two whole strips have vanished from his invoice.
(a + b)² = a² + 2ab + b²Open the case →The vanishing corridor
Two opposite corridors cancel. Pip has already booked both.
(a + b)(a − b) = a² − b²Open the case →The triangle that lost a corner
Pip folds three corners into one straight queue. Nobody gets to jump the line.
α + β + γ = 180°Open the case →Four triangles and one vacancy
Four identical guests occupy a square hotel. The empty room solves the mystery.
a² + b² = c²Open the case →The pigeon who built a square staircase
Pip adds one odd-shaped border each day. Mika discovers a square hiding in the stairs.
1 + 3 + 5 + ⋯ + (2n − 1) = n²Open the case →You know every case in this selection. Show known cases or explore another topic.
A bigger mystery is waiting
You do not have to finish this shelf first. Pick a connection whenever curiosity strikes.