funlean.

NO TIMER · ONE STORY AT A TIME

Start with a cake.
Find one reason.

Take three cakes from both sides.
Why do the scales stay balanced?

You do not need formulas or Lean yet. Begin with the short story, and we will guide the next action.

Read the first story →

Your first stop: The cake scale conspiracy.

The same operation on both sides.x + b8=x + (3) = 8
A comic and a diagram tell the same small story.

What will I do?

  1. 1

    Read a little

    Meet the words, then read one comic panel at a time.

  2. 2

    Move and notice

    Use “Next” and the sliders to connect the picture to its reason.

  3. 3

    Look back

    Try two small checks, see what changed, and save a place to continue.

If you feel lost, open “Help” at any time. You can go back; nothing is timed.

I know where I want to go
Choose among eight small stories →
Read the Fermat storyFollow the full proof knowledge route

Knowledge pages · Tea salon · Proof stories

I’m lost · Help

Mika’s help desk

One thing at a time

Start with the cake-scale story. You only need to read one small piece at a time. If you are in the Fermat story, start with Story depth, then the words listed before the chapter.

In simpler words

You do not need to know Lean, symbols or university mathematics to begin. Definitions come first in the small stories.

A small clue

Look at the small example before the general formula. Ask what changed and what stayed the same.

Close this panel to return to the exact place you were reading. These are prepared hints for this page.

Start with the first small story →