You name it, your tutor builds it
Type a concept, a skill, a paper. It interviews you for a minute, then writes a course around what you already know — not around what a catalogue happens to have.
Name a topic.
Get a course
built for you.
Type any topic in your own words. A tutor interviews you for three questions, proposes a plan you approve, then builds the course while you put your phone away. Lessons teach before they test.
Start on the web
iOS — coming soon
Web app live now
Free to start · no credit card · works on the Underground
- Teach, then test
- 2–5 question interview
- ~20s to lesson one
- Offline lessons
- Streak · XP · league
Before the question
A discount rate turns money you get later into money
you can compare to money you have today.
Your model raises the discount rate. What happens to the present value?
A
It falls — later cash is worth less today
BIt rises
CIt stays the same
Right — and that is the whole intuition.
Continue
Try a lesson
A lesson explains before it asks.
Pick a topic and take its first lesson right here. It opens with a short explainer, then asks while the idea is still warm — four kinds of question, chosen to suit the idea. Tap an underlined term for its definition.
Five sample lessons · no sign-up · nothing is saved
Turn on JavaScript to try a lesson.
The one loop
Five minutes in, a course that fits you.
No catalogue to browse and no course to pick. You say what you want; the interview works out where you already are, and the plan is yours to approve before a single lesson is written.
-
New course
What do you want to learn?
Name it in your own words. Your tutor asks a few questions, then builds the course around what you already know.
DCF models for my new analyst job
33 characters StartNegotiating a salary Kubernetes, for real Reading a balance sheet01Name it
A concept, a skill, a paper you have to understand by Thursday. Your words.
-
← DCF models for my new analyst job question 3Have you built a spreadsheet model before? Yes — budgets, at my last job Which of these could you explain to a colleague today?Pick all that apply ✓Present value Discount rates Terminal value Continue02
Get interviewed
Two to five adaptive questions. Nothing to type — it is asking, not testing.
-
← DCF models for my new analyst job plan readyPresent valueThe course I'd buildDCF for new analysts 12 lessons · 4 units · 5 min each
Build a DCF you could defend in your first model review.
What you'll learn- Time value — why later cash is worth less
- Discount rates — picking one you can defend
- Terminal value — where most of the number hides
Build it Edit03Approve the plan
A proposal streams in: units, pace, depth. Change it or say go.
-
Monday 14 September 9:42
PolySkill
now
Your course is ready
DCF for new analysts — lesson 1 is waiting.
04Put the phone away
The outline and lesson one land in about twenty seconds. The rest follows.
-
14 day streak0/100 xpTuesday
Good morning.
Pick up where you left off Discount rates →League 4th of 30 promotion at 5th05Come back tomorrow
A streak, a daily goal and a league keep yesterday from leaking away.
The tutor never leaves
Too easy, too slow, wrong angle? Say so.
The tutor that interviewed you stays with the course. Tell it the pace is wrong or that you need the finance version rather than the textbook one, and the remaining lessons are rewritten around you — not reset, rewritten.
- It shows its work. You see what it is changing before it changes it.
- Ask mid-lesson. A question about the thing in front of you, answered in context.
- Harder on request. Finished a unit and it felt thin? Ask for a steeper one.
Unit 2 is going well — three lessons, no misses. Want to keep this pace?
honestly it's too easy. I do this at work
Understood. I will skip the arithmetic warm-ups and take the remaining lessons
straight to modelling decisions.
Rewriting unit 3
Done. Four lessons, same length, and the checkpoint now asks you to defend a rate
rather than compute one.
Why it sticks
Built for the five minutes you actually have.
A train ride is a real session. Everything here is shaped around that: short lessons, no loading screens where there should be learning, and a phone that keeps working when the signal does not.
Every lesson teaches, then tests
A short explainer first — a diagram, a worked example, plain language — then a handful of questions while the idea is still warm.
Five minutes is a real session
Built for the train ride. Lessons are pre-downloaded, so they open on a dead connection and your answers sync when you surface.
Gamification that stays quiet
Streak, XP and a weekly league — rendered as soft geometry rather than confetti, because the topic is often someone's job.
Calm, not carnival
The numbers are there when you want them, and never in the way.
Every number is the server's — predicted on your phone while you are offline, then settled the moment the truth arrives.
Streak
14
days, and it forgives one
Daily goal
40 / 50 XP
League
4th
of 30 · promotion at 5th
This week
6
lessons · 1 checkpoint passed
Where to find it
Open it in the browser today.
The web app is the whole product — same courses, same tutor, same offline store. The phone builds are on the way, and your account carries across.
Live
Web
Everything, in any modern browser. Sign in with Google and start a course in under a minute.
web.polyskill.app
Coming soon
iOS
In TestFlight now, with notifications for your daily goal and lessons kept on the device. App Store to follow.
Coming soon
Coming soon
Android
Built from the same codebase as iOS and the web, so it arrives with the whole product rather than a cut-down one.
Coming soon
Questions
The short answers.
What can I ask it to teach me?
Anything you can describe. People use it for the thing their new job assumes they know, the paper they have to present, the language of a team they just joined, and the hobby they keep half-learning. If the topic is too broad, the interview says so and narrows it with you.
How long until I can start learning?
The interview takes about a minute. The outline and your first lesson land roughly twenty seconds after you approve the plan, and the rest of the course is written while you work through it.
Does it work without a connection?
Yes. Upcoming lessons are downloaded to the device before you need them, your answers queue up while you are offline, and your XP and streak are predicted locally against the same formula the server uses — so the numbers do not jump when you surface.
What if the course is wrong for me?
Tell the tutor. Too easy, too slow, wrong examples, wrong emphasis — it rewrites the remaining lessons around the correction rather than starting you over.
Is the iOS app available?
Not yet. It is in TestFlight and the App Store release is next. The web app at web.polyskill.app is the full product in the meantime, and your account, courses and streak carry over when the phone app ships.
What do you want to understand?
Name it in your own words. In about a minute you will have a plan, and in twenty seconds after that, a first lesson.
Start on the web
iOS — coming soon