Start with Scroll 1 — the number line. Ten minutes, a few widgets, your first belt.
Start Scroll 1 →🥋 Your belt rack
🥋 Basic training — read, poke, earn belts
The Number Line & the Number Clans
Every number has a home on one endless line — even the cold ones below zero and the sneaky ones hiding between the whole numbers. Meet the clans: counting numbers, integers, fractions and more.
Start training → Scroll 2The Secret Moves of Math
Commutative, associative, distributive… scary words for simple ninja moves that let you swap, regroup and split numbers to make hard sums easy. Learn the moves, then use them everywhere.
Start training → Scroll 3The Kata — Order of Operations
Why does 3 + 4 × 2 make 11 and not 14? Because math has a kata — an exact order of moves called BODMAS or PEMDAS. Race the robots, learn the four ranks, and dodge the famous left-to-right trap.
Start training → 🏯 TrialThe Grand Dojo
Mixed questions from every scroll you've trained, shuffled — because real mastery is knowing which move. The only place the 🖤 Black belt can be earned. Unlocks once you hold belts from two scrolls.
Face the trial → Scroll 4Coming soon…
New scrolls are being written by the elders. Balancing equations, powers, and more mysteries of algebra await.
🏛️ the vault · advanced concepts visit the Vault →
The scrolls teach you the moves. The Vault shows where they come from — big, beautiful ideas proved by legendary mathematicians. The format: watch a short video, then poke the proof with your own hands. No belts, no dojo, no rush. Just wonder.
Wing 1 · taming infinity
Why is a circle's area π × r²?
Archimedes traps a circle with a 96-sided polygon, and pizza slices rearrange into a rectangle. Bathtubs, ship-grabbing claws, and the method of exhaustion included.
Open → 🍫 Vault № 2The snack that never ends: ½ + ¼ + ⅛ + … = 1
Eat half, then half of what's left, forever — and finish exactly one bar. Zeno's 2,500-year-old "you can never reach the door" trap, and the limit that escapes it.
Open → 🃏 Vault № 3Add ten numbers in one second
The odd numbers 1 + 3 + 5 + … secretly build perfect squares — count them, square the count, done. Pebble-math from the Pythagoreans, a party trick for you.
Open → 🎭 Vault № 4The proof that lies: π = 4 ?!
The internet's favorite fake proof — every step true, conclusion false. Fold the square, fall for it, then zoom in and catch the lie. A defense class for your brain.
Open →Wing 2 · slicing & stacking
The circle's third key is an onion
Peel the circle into rings, unroll them, stack them — a triangle appears and πr² falls out. A 900-year-old proof that is secretly your first integral.
Open → 🏀 Vault № 6Measuring a curve — exactly
Archimedes fills a parabola with endless triangles, each generation ¼ of the last, and sums the series exactly — in 250 BC, with receipts.
Open → 🪦 Vault № 7The shape on the tombstone
Why Archimedes chose a ball-in-a-can for his grave: slice by slice, the sphere's share of its cylinder comes out perfectly clean. Coin stacks, a lost book, and tennis balls.
Open → ❄️ Vault № 8A shape with an endless edge
The Koch snowflake fits in your hand but its border never ends — edge → ∞ while area stays finite. Two infinities, one shape, plus the coastline paradox.
Open →Wing 3 · the calculus eye
How fast — right now?
The falling ball's 1, 3, 5, 7 finally explained: steadily growing speed, seen from outside. A prediction game, and your first derivative.
Open → 🔍 Vault № 10Why is your street flat on a round planet?
Zoom into any smooth curve and a straight line appears — that's why Earth feels flat. The snowflake refuses, and that refusal is the dividing line of calculus.
Open → 🐌 Vault № 11The pile that breaks the rule
½ + ⅓ + ¼ + … shrinks forever, yet Oresme's 1350 grouping trick shows where it's headed. Plus a block tower that leans past the table edge.
Open → 🎺 Vault № 12Fill it — but never paint it
Gabriel's horn holds three liters of paint but its wall can never be painted. Both proven. Torricelli's headache, resolved by asking: which quantity?
Open →Every Vault video, mobile-vertical — one swipe at a time. Swipe in →
Short bits of text with pictures and widgets you can drag, click and play with. No walls of words.
Select any sentence and an “Ask about this” button pops up. Sensei — our AI helper — answers just for you. Nothing you ask is saved or shown to others.
Answer 5 questions in your own words. Sensei reads each one, cheers when you nail it, and gives you hints when you don't. Earn belts!