Back to Blog
October 28, 2026

AI Tutors Matched Experts in a One-Hour GRE Study. What Brings Students Back Tomorrow?

A
MOOBON Axiom Team
Engineering & Learning Design

A new study has put AI tutors and expert human tutors side by side, with randomly assigned students and a control group. For one hour of GRE preparation, students taught by AI learned about as much as students taught by experts.

That is a promising result. It is also a specific one. This article looks at what the study measured, what it leaves open, and what that means for schools and tuition centres.

What the study did

The paper is StudentBench, a preprint published on arXiv in September 2026 by researchers at Handshake AI (arXiv:2609.28470). As a preprint, it has not yet been through journal peer review.

  • 2,383 participants were randomly assigned to one of three groups: an AI tutor, a human tutor, or a control group that watched unrelated educational videos.
  • Each took a 27-question GRE test (the US graduate admissions exam), spent one hour in their group, then took a second test of the same length with different questions. The order of the two test forms was swapped at random, so a harder form could not pass for learning.
  • The human tutors were experienced: former writers of GRE questions at ETS or Kaplan, or tutors with at least five years of GRE teaching. They taught one-to-one over video.
  • Thirteen AI tutors were tested, from expensive frontier models to small open-weight ones.

What it found

  • On this measure, AI tutoring was statistically equivalent to expert human tutoring. The difference in learning gains was about half a percentage point, inside the equivalence margin the researchers set.
  • Both did better than the control. AI tutoring raised scores by about 6 percentage points more than the control group, roughly one and a half to two more correct answers out of 27, after a single hour.
  • The best AI tutor had a higher average gain than the human tutors in five of the seven GRE topic areas.
  • One small model reached gains equivalent to the human tutors at far lower cost. Comparing that model's inference cost with the cost of human tutoring, per percentage point gained, it was roughly 900 times cheaper. That figure is about one model in this study, not the cost of running a full learning service.

The paper also reports a pattern in the Quantitative (maths) sections. Faster AI replies were associated with more messages from students, more messages with more correct practice, and more correct practice with larger gains. These are associations, not a tested cause, but they are worth noticing.

What it does not show

The authors are clear about the limits.

  1. Only short-term gains were measured, straight after the session. How much remains weeks later is unknown.
  2. Participants were English-speaking adults (median age 21) recruited for a paid study. Results may differ for teenagers, other languages, or other settings.
  3. There was no group that practised GRE questions without a tutor, so the study cannot separate the effect of the AI's teaching from the effect of an hour of focused practice.
  4. The study measured learning inside a structured, paid research session. It did not test whether students would choose to start the same session on their own, or return to it over the following weeks.

The fourth point is the one this article is about.

A promising hour, and an open question

The study answers one question well: within a structured session, can AI support short-term exam learning as well as an expert tutor? For one hour of GRE practice, the evidence says it can.

Whether that opportunity becomes part of a student's ordinary week is a separate question, and one the study did not test. As we wrote in Learning to Study Still Takes Support, many students who stop are not missing a better explanation. They are missing a reason to start, a manageable next step, and someone who notices when they have gone quiet.

Short-term learning gains from AI look promising. Turning them into everyday learning still needs to be worked out.

What this means for schools and tuition centres

AI can make practice and timely feedback available beyond what one teacher can provide alone. Teachers can use the resulting information alongside their knowledge of each student to decide when to intervene, what to explain differently, and how to support the next attempt. During a lesson that might mean spotting a misunderstanding the practice revealed. Between lessons it might mean checking in with a student who has gone quiet.

Software can help students restart too, with a sensible next question or a reminder of where they left off. But the decision about how to support a particular student, at a particular moment, is still best made by someone who knows them.

How we read it at Axiom

The findings are consistent with our emphasis on active practice: students need opportunities to attempt problems, receive useful feedback, and try again. On Axiom, a wrong answer is followed by a one-line reason and a similar question to try, rather than a page to read.

The association between faster replies and greater participation is also familiar to us. We have spent a lot of effort making marking and the next question arrive quickly, because a student waiting for feedback is a student who may close the tab.

The study also leaves open a question that Axiom for Schools is designed to address: how can effective practice become part of a student's regular learning routine? Teachers see per-topic progress for each student and who has been inactive for a week or more, so they can decide when and how to step in. Inactivity is a prompt to check in, not a diagnosis: a student may be studying elsewhere, busy, or unsure how to continue.

The next question

In a one-hour GRE study, AI tutoring produced short-term learning gains statistically equivalent to expert human tutors. For one model, inference cost per percentage point gained was far below the corresponding human tutoring cost.

The next question is whether students return, practise regularly, and retain what they learn. Schools and tuition centres can help test that in everyday learning, with teachers who know when a student needs a different explanation, a smaller next step, or a conversation.

If you run a school or tuition centre, see what your teachers would see.

Run a school or tuition centre?

See Axiom for Schools