Diagnostic language engine · grade by grade

The language engine that shows its reasoning.

Vaaani builds a living picture of every child — what they know, what they’re ready for, what’s slipping away — and picks each lesson from it, with a reason it can show you. Built out from the child’s home language. Not a chatbot. A glass box.

No black box — every choice is out in the open, not a chatbot English as a second language, Indian classrooms Works on the computers you already have — nothing to install
vaaani · learner #217 · live decision
today’s focus

She knows “phone”, she knows the /f/ sound — time to join them

Two things she already knows, but hasn’t joined up yet. Fixing this one link also makes photo, graph, laugh easier.

Just the right challenge — about 68% likely to get it, with room to learn.

what she knows so far
the /f/ sound — solid0.81
spelling “ph” — still shaky0.34
the word “phone” — getting there0.52
how it comes out · still on paper — 7.2s, two tries
why it slipped last time
sound and spelling not joined up yet.62
hasn’t met it often enough.23
a habit from her home language.11
“The link between the sound and how it’s written isn’t solid yet — we’ll practise that exact pair.”

Why schools choose us

You can defend a decision you can see.

Most classroom AI is a large language model in a wrapper — helpful, but you cannot say why it taught what it taught. Vaaani was built the other way round.

Typical AI tutor

A black box

  • A chatbot decides what to show — you can’t see why
  • “Personalised”, but nothing you can actually look at
  • Hands over the answer; the thinking stays hidden
  • Never checks whether it was right
  • Sends the child’s work off to a cloud
Vaaani

A glass box

  • Every lesson is chosen for a reason it shows you
  • Keeps a living picture of your child — open it and read it
  • Tells you why it chose, and how likely it is to work
  • Checks its own guesses against what really happened
  • No name, no account — never sent to an outside AI

Inside the glass box

Five instruments, one growing child.

No large language model anywhere in the teaching decision. Just an inspectable, estimated state and explicit reasoning — the kind a linguist, not a chatbot, would use.

The Cognitive Twin

A living picture of what your child knows — it updates with every answer, and fades gently over time, the way real memory does. Every lesson is picked for your child alone, so no two children follow the same path.

‘tri-’ words (three)0.74
‘aqua-’ words (water)0.41

CASCADE — a web, not a list

Words are learned in a web, not one at a time. Master one link and the words next to it get easier — learn the /f/ in “phone” and photo, graph, laugh come along for the ride.

phonephotographlaughtough

The Cause-net

When your child gets something wrong, it works out why — the spelling isn’t linked to the sound yet, not enough practice, or a habit carried over from the home language — then fixes that exact thing.

home-language habit.58
not enough practice.27

Calibration — it keeps score

Before each lesson it predicts how your child will do, then checks itself against what actually happened. A teacher honest enough to grade its own guesses.

guessed 70% · she scored 68% · honest

Fluency — paper vs. real time

Knowing a rule and using it in the moment are not the same thing. This watches how the answer arrives — fast and sure, or slow and second-guessed — and tells effortful recall apart from real command. A correct answer that took eight seconds and two tries isn’t mastered yet, and it says so, so a child is never marked “done” on a skill they can only manage on paper.

in real time — fast, first try0.92
on paper — slow, self-corrected0.34
answered in 1.8s · first try · automatic — really hers now

The unfair advantage

Bridged from the mother tongue.

An Indian child learning English is not a blank slate — they already own an isomorphic web in Hindi, Bangla, Tamil. Vaaani grafts that head start onto the English graph, and reads L1 into why a sound is hard.

A Bengali speaker saying “jero” for “zero” isn’t making a mistake — Bengali has no /z/. The engine knows that, and teaches from it.

“Why do Bengali speakers often say jero instead of zero?”
Bengali doesn’t have the /z/ sound, so the brain maps it to the nearest one it owns, /dʒ/. That’s your mother tongue’s phonology at work — not an error. Now: which English sounds does your first language lack? Let’s find them.

Run a pilot

See it work on your own students.

We start small and honest — a single cohort, real children, measured results you can read line by line.

01

Pick a cohort

One class or centre. Set the home languages. No installation — it runs in the browser, on a phone or a lab machine.

02

Children do lessons

Each child works through short lessons. The picture of what they know fills in; every choice records why it was made and how likely it was to land.

03

Read the evidence

You see what each child knows, why they slipped, and how well the engine’s own guesses held up — not a mystery score.

Where we honestly stand: a first small pilot (7 children) is complete; the engine’s starting numbers come from published research and get sharper as real pupils use it. We show what we’ve actually measured — and flag anything that’s still an estimate.

Bring a tutor that can explain itself to your school.

Give one cohort an engine that knows each child — and can prove it. We’ll set up your pilot personally.