Every variable is yours
Nothing here is a static diagram with a play button. Change the inputs and the outcome re-renders under your hand — which is how intuition gets built instead of trivia.
Free to try · limited-time betaDon't
Don't
memorize it.
Play with it.
Play2Lrn turns the concepts that never quite stick — ad auctions, projectile motion, search intent — into simulations you can drag, break and replay. Move one control and the idea explains itself.
No card · nothing to install · 11 categories and growing
Live — drag me
physics / projectile motion
Range
602 m
Peak
193 m
Hang time
12.5 s
52°
78 m/s
Drag a slider. Notice you now know why 45° goes furthest without anyone telling you.
Concepts you can play with include Ad Rank, Quality Score, Projectile motion, Search intent, Gradient descent, Second-price auctions, Overfitting, Terminal velocity, Attribution windows, Titration curves, Neural nets, Conversion lag.
How it usually goes
Read it. Re-read it. Highlight it. Forget it.
- A definition you can recite but not use.
- A diagram that never moves.
- A worked example with someone else's numbers.
- Thursday, and it's gone.
How it goes here
Grab a control. Break the thing. Now you know.
- Every variable is a slider you can move.
- The output redraws the instant you touch it.
- Your numbers, your experiments, your mistakes.
- Understanding you can rebuild from scratch.
The library
Pick a shelf. Everything on it is free to try.
New simulations land regularly — search or filter by category to find one.
Free to tryFinance
Understanding Compound Interest
Model how wealth is created by the power of compound interest and experiment with different scenarios.
Play with itWhy it sticks
Interactive isn't a gimmick. It's the whole method.
Understanding arrives when you can predict what happens next. That only comes from turning the knob yourself and being wrong a few times.
One tab, zero setup
No installs, no lab kit, no downloading a 400 MB simulator. Every simulation runs in the browser and resizes to whatever screen you opened it on.
Science and business, same shelf
Search ad auctions sit next to projectile motion. If a concept is easier to feel than to read about, it belongs in the library — whatever field it came from.
Made to be shown
Clean enough to project in a classroom or drop into a client call, and quick enough that nobody is watching a spinner while you explain the setup.
Three steps, about a minute
From 'I've read this before' to 'oh, that's what it does'.
- 1
Pick the fuzzy one
Filter by category, or just scan for the concept you've quietly been nodding along to for years.
- 2
Move something
Drag, launch, mix, bid. There is no wrong input — the wrong inputs are where most of the learning is.
- 3
Watch it click
The moment the output changes with your hand on the control is the moment it stops being something you memorized.
Limited-time beta
The whole library is free to try — for now.
No credit card. No countdown timer in the corner. Create a free account, open anything on the shelf, and keep playing for as long as the beta is open. Paid plans come later, and we'll say so well before they do.
Before you ask
The short answers.
Do I need an account just to look around?
No. Browsing the library and reading what each simulation covers is open to everyone. You need a free account to actually run one — that's how we keep them stable and work out what to build next.
How long does 'free to try' last?
The full library is open for the duration of the beta. When paid plans arrive we'll announce them well in advance rather than switching anything off overnight.
Will these work on a phone?
They run in any modern browser and scale to the screen. The denser ones — anything with several controls at once — are considerably happier on a laptop or a projector.
Can I use these to teach?
Yes. Project them, share the link, or hand the controls to whoever you're explaining it to. Letting someone else drive is usually the fastest route to the penny dropping.