Three kinds of product already exist. Each is missing the same thing in a different place.
- Course platforms
- Progress is a percentage of video watched. That measures how much went past, not what you can do — and once you fall behind there is no way back in except the beginning.
- Solvers and answer apps
- They settle one question and leave nothing behind. Nothing accumulates.
- Gamified apps
- Enjoyable, but the structure stays invisible. Where you are, what is missing underneath, and what you could sensibly learn next are never shown to you.
1The tree is the product, not the decoration
The plan is to put your own graph on the first screen: lit for what holds, dim for what is slipping, outlined for what your prerequisites already allow. One object that is the progress bar, the map and the record at once, rather than three widgets that disagree.
Today: the graph and the renderer exist. The learner state that would colour them does not.
2Start where you actually are
Someone five years into a job who wants probability should not have to begin at what a fraction is, and should not be dropped into measure theory either. The way in is designed as a short placement that walks the prerequisite chain by halving, and hands back a starting point rather than a score.
Today: the placement logic is written as a pure function with tests. There is no screen for it.
3How you think is the second axis
Concepts run in one direction. Reduction, invariants, symmetry, limiting processes, construction, proof by contradiction — the moves themselves run in the other. Each fragment carries exactly one thinking tag, so getting better at mathematics becomes a second thing that can be counted instead of a feeling.
Today: 13 tags are defined, each with a written rationale and worked examples. 48 of the 69 concepts carry at least one; the rest are deliberately untagged, because a label on everything means nothing.
4Review is the default, not a feature you remember to use
Strength decays, so the tree dims on its own. A day is meant to be one new fragment plus whatever came due, which means you never have to decide what to revise — and coming back after three weeks away costs you nothing worse than a slightly darker tree.
Today: the scheduling rules are written and tested. They act on concepts rather than flashcards, so one wrong answer dents a concept instead of resetting it.