Four practice apps for skills that reward a few minutes a day: typing speed and accuracy, mental arithmetic, world geography, and reading JavaScript. Each one is built around short sessions with immediate feedback, and each one keeps your progress in this browser rather than behind an account.
- 01
Warm up before you work
A single 60-second typing passage or one timed arithmetic set is enough to get moving, and both report what to fix rather than only what you scored.
- 02
Turn a weak spot into a drill
The typing trainer names the keys and digraphs that cost you accuracy; the math gym reports speed per operation, so you can see that division — not multiplication — is what slows you down.
- 03
Learn the map by using it
Practise countries, capitals, and flags against an interactive world map, so a place is learned by its position rather than as an item in a list.
- 04
Get better at reading code
Predict what a snippet prints, then step through the trace and see where your model of the language diverged from what actually happened — the fastest way to fix a misunderstanding.
Progress stays on your device
Scores and streaks are written to this browser's local storage. There is no account, no leaderboard, and no profile — which also means clearing site data resets you to zero.
Accuracy counts, not just speed
A typing score that ignores errors rewards the wrong habit. The trainer reports speed and accuracy together and highlights the keys behind the mistakes.
Short sessions by design
Every app is built around a session you can finish in a minute or two, because a daily minute beats an abandoned hour — and nothing here nags you to come back.
Code that really runs
Reading challenges execute in a sandboxed worker in your own browser, so the trace you compare your prediction against is real output rather than a stored answer key.
Free and unmetered
No sign-up, no trial, no daily limit, and no advertising interrupting a timed run.
Works offline
Once a page has loaded, practice continues with the network disconnected — including on a phone or a locked-down machine.
Do I need an account to save my progress?
No. Progress is stored in your browser's local storage, on this device. That keeps practice private and instant, with the trade-off that it does not follow you to another browser and is cleared if you clear site data.
What is a good typing speed?
Around 40 words per minute is typical, 60–70 is comfortably fast, and above 90 is unusual. Accuracy matters more than either: raw speed with a 90% accuracy rate is slower in practice than a steadier pace with few corrections, which is why both are scored.
How should I practise mental arithmetic?
In short timed sets, focused on the operation you are slowest at rather than the one you enjoy. The gym reports speed and accuracy separately for addition, multiplication, and percentages so the weak one is obvious.
Is the code in the reading challenges actually executed?
Yes, in a sandboxed web worker in your browser. That is what makes the execution trace trustworthy — you are comparing your prediction against a real run, not against a written explanation.
Are these suitable for children or classrooms?
There is nothing to sign up for, no chat, no advertising, and no data collection, so they work in a classroom. The typing and geography apps in particular are commonly used that way.
Do the apps work on a phone?
Mental math, geography, and code reading do. Typing practice needs a physical keyboard to be meaningful, so it is best on a laptop or desktop.