Beta
Vetus — by OffAxis
The answer tells you what. The question teaches you why.
Every other AI hands you the answer. Vetus hands you a question — then another, then another — until your understanding is either real or visibly incomplete.
Free while in beta. No sign-up wall to try one session.
You said
The derivative of a constant is zero.
Vetus asks
Your reasoning
Explain your reasoning…
Follow-up 3 of ∞
Submit reasoning
Our grades went up.
Our understanding went down.
Both things are true at once, and they are related.
This is not a hunch.
AI arrived in education faster than any technology before it. The research on what it did to us is starting to arrive too.
94%
of students now use generative AI for assessed work — up from 53% two years earlier.
HEPI Student Generative AI Survey 2026 ↗83%
of people who wrote an essay with AI could not quote a single line of it — sixty seconds after submitting. The groups who used a search engine, or nothing at all, had no such trouble.
MIT Media Lab, Your Brain on ChatGPT, 2025 (n=54) ↗↓
The heaviest AI users scored the lowest on critical thinking. Across 666 participants, the link ran through “cognitive offloading” — handing your thinking to the tool. The youngest participants were the most dependent, and scored worst.
Gerlich, Societies, 2025 (n=666, correlational) ↗None of this makes students the villain. When the only thing being measured is the answer, producing the answer is the rational move. The measurement is what’s broken.
So we asked a stupid question.
What if the AI asked you?
Not a quiz. Not flashcards. An interrogation: one that goes after the belief underneath your answer, notices when you’re pattern-matching instead of reasoning, and refuses to move on until you can say why.
A lecturer with two hundred students cannot sit with each of them and probe what they actually understand. That is not a failure of teaching. It is arithmetic.
An AI can.
This isn’t about being anti-AI. It’s about the fact that we’re using it in the way that makes us dumbest.
One loop, repeated until it holds.
01
Choose what to master
Calculus. Physics. Philosophy. You pick a domain and Vetus starts where you actually are, not where a syllabus assumes you are.
Learn
What do you want to master?
Calculus→
Classical mechanics→
Epistemology→
Linear algebra→
Probe
What do you think you understand?
LimitsConfident
ContinuityFairly sure
DerivativesShaky
02
It finds out what you think you know
Before it teaches anything, Vetus probes. It’s mapping the shape of your understanding — and the shape matters more than the score.
03
It names the weakness out loud
Vetus doesn’t just mark you wrong. It tells you what kind of wrong — memorised where you should have reasoned, procedure where you needed principle.
Tutor insight
“Your understanding of ‘Limits’ seems rule-based. Shall we explore why they exist?”
Explore why
Later
Derivatives — question 4
What is the derivative of a constant function?
Pick one — then Vetus asks why
Explain your reasoning…
04
Every answer is followed by “why?”
You’ll get multiple choice. Then you’ll be asked to defend it in your own words. Getting it right by accident doesn’t survive the follow-up question.
← Try it. Pick any answer.
05
Your understanding becomes a map
Every session updates a live picture of what you hold firmly, what you hold loosely, and what you only think you hold. Gaps stop being invisible.
MapPathInsights
HeldLimits
LooseContinuity
HollowChain rule
HollowOptimisation
LooseSeries
HeldIntegrals
The whole interrogation, in your pocket.
Four screens, one loop. Pick one to see it — the phone follows.
Fair warning: this will feel worse than ChatGPT.
It should. In a Harvard study, students taught through active engagement learned measurably more than students given polished lectures — and believed they had learned less. The effortless option felt better and taught less. The effortful one felt worse and worked.
Deslauriers et al., PNAS, 2019 ↗
Vetus is the effortful one. It will make you sit with a question you can’t immediately answer. That friction isn’t a rough edge we haven’t sanded down yet. It’s the product.
If you want the answer, you already have twenty tools for that. This one is for when you want to actually know.
Students
For the subject you’re passing and don’t understand. Find out which one that is before the exam does.
Self-teachers
No lecturer to check your reasoning against? Vetus argues back.
Educators
The individual attention arithmetic never allowed you to give. See where a cohort’s understanding is genuinely thin, not just where the marks fell.
The doubts, answered.
Is this just a quiz app?
No. A quiz checks whether you produced the right answer. Vetus checks whether your reasoning holds — and every question is followed by “why?”
Will it give me answers if I’m stuck?
Yes. It teaches when you genuinely don’t know. What it won’t do is hand you the answer before finding out whether you needed it.
Isn’t using AI to fix AI a bit circular?
The problem was never the technology. It was pointing it at the answer instead of at the understanding. Same tool, opposite direction.
Does this replace my lecturer or my textbook?
No — it’s the thing neither can scale. A textbook can’t notice you’ve memorised a rule without grasping it. A lecturer with two hundred students can’t either.
Is it free?
Free during beta.
Find out what you don’t actually know.
One session is enough to see it. It takes about ten minutes and it’s mildly humbling.