What this site is
Three Basic scrolls teach foundations (number lines, properties of operations, order of operations) with widgets to poke and an AI-checked Practice Dojo where kids earn belts. The Vault holds twelve watch-then-wonder lessons โ short videos plus hands-on demonstrations of big ideas (limits, proof, the first steps toward calculus). Everything is free. There are no ads, no accounts, no leaderboards, no streaks, no coins, and nothing to buy.
Exactly what leaves the browser
- When your kid asks Sensei a question (or answers a Dojo exercise), the question, the highlighted sentence, and the recent back-and-forth of that exercise are sent over HTTPS to our small server, which passes them to Anthropic's Claude โ the AI that plays Sensei โ to write the reply.
- Our server keeps no database and no record of the text; it holds only short-lived, in-memory counters (per-visitor rate limits) that vanish on restart.
- Anthropic processes the text to generate the answer, under its privacy policy; API inputs are not used to train its models by default.
- Nothing else is sent anywhere. Watching videos and playing with widgets happens entirely in the browser. The only third-party requests are Google Fonts (the typefaces).
What is stored on your device
- Belts and practice progress are saved in this browser's localStorage โ on the device, not on any server. That's why there are no accounts.
- The honest trade-off: progress doesn't follow your kid to another device, and clearing the browser's site data erases it. To reset on purpose: clear this site's data in the browser settings.
About Sensei (the AI)
- Sensei is an AI and the site says so. It's instructed to stay on math, to coach with hints rather than hand out answers in the Dojo, and to keep replies short and kind.
- AI answers can occasionally be wrong or oddly phrased. We validate replies before showing them and rate-limit usage (per-minute and per-day caps per visitor, plus a site-wide daily cap), but a grown-up's judgment beats an AI's โ if an answer looks off, it might be.
- Conversations aren't saved. We couldn't show you a transcript if you asked โ that's the design.
What your kid is learning
Basic training covers the number line and integers, properties of operations (commutative, associative, distributive), and order of operations. The Vault's three wings preview the ideas behind calculus honestly at a 10โ12 level: infinite series and limits (Wing 1), areas and volumes by slicing (Wing 2), and rates of change (Wing 3). The history in the story cards is told playfully but fact-checked โ attributions are real (Eudoxus, Abraham bar Hiyya, Oresme, Torricelli), and every lesson's footer separates legend from record.
Accessibility
All videos have captions. Lessons work on phones and computers. If something is hard to use for your kid, we want to know.
Questions
This site is made by one person, with care. Something broken, worrying, or confusing? Write to swaroopgn@gmail.com.