TeachBack

The student does the teaching.

TeachBack is a Hebrew-first learning tool. You bring your own study material, then explain it out loud to Lumi, who only ever asks questions. The gaps show up the moment you try to say something in your own words and cannot.

This page is the English overview. It is written plainly, including about the parts that are not finished, because a page that oversells is not worth reading.

See the loop, start to finish Read the Hebrew site

The worked example needs no account and no microphone. Nothing on it is assessed.

How it works

  1. Bring your material

    A PDF, a summary, lecture notes. The topics are pulled out of what you uploaded, so the session is about your material and not a generic syllabus.

  2. Explain it out loud

    You talk. Lumi listens and asks. She is written as a curious ten year old who keeps asking why, and she never explains the topic back to you, because the moment she does, you stop being the one doing the work.

  3. Find the part you could not say

    The useful moment is not praise. It is the question you could not answer, which is usually the exact thing you would have discovered in the exam instead.

Reading about a loop is a poor substitute for seeing one. The worked example walks through a full session on HTTP caching, including the learner getting something wrong and correcting themselves. It is a written example and it says so on the page.

Why teaching, specifically

Explaining out loud is not a gimmick wrapped around a chatbot. It is the part with the strongest evidence behind it, and the design follows what that evidence actually requires.

Students who practised retrieving material from memory recalled 80% on a delayed test. Students who simply reread it recalled 36%, while predicting the opposite result for themselves.

Karpicke & Roediger, Science, 2008. 10.1126/science.1152408. This tests retrieval practice, which is what a teach-back session makes you do.

Across 39 studies, teaching produced a real learning benefit when the student knew in advance they would teach (g = 0.48). Teaching without that expectation produced no benefit at all (g = -0.02). Interactive teaching, with questions coming back, beat one-way explaining.

Lachner, Backfisch, Hoogerheide, van Gog & Renkl, Educational Psychology Review, 2024. 10.1007/s10648-024-09851-2. This is the finding the product is shaped around: you know Lumi is waiting, and she asks back.

A review of 19 experiments on learning by teaching found 17 with positive effects, median d = 0.77.

Fiorella & Mayer, Learning as a Generative Activity, Cambridge University Press, 2015.

What these studies are and are not. They test retrieval practice and learning by teaching as methods, in classrooms and labs. None of them is a study of TeachBack. They are the reason the product is built this way round, not evidence about how well this particular implementation works. That evidence would have to come from measuring real sessions, and it does not exist yet.

What this is, plainly

Language
Hebrew first, and built for Hebrew speakers preparing for exams. The interface has an English mode, which is still being finished.
Voice
Real-time spoken conversation in the browser. There is a text mode too, for when speaking out loud is not an option.
Cost
Free, with no card. It is free because it is early and the people using it are teaching us what to build.
Account
Google sign-in, and a microphone for the voice sessions. Neither is needed for the worked example.
Built by
One person, in Israel. TeachBack is not a funded team and does not pretend to be one.
If you want the engineering side, how TeachBack is built covers the decisions, the architecture that enforces them, and what is deliberately not finished.

Try it

If you read Hebrew, the app is the real thing and the worked example is only a description of it.

Open the app Or read the worked example first

The app is Hebrew-first. English support in the interface is partial and still landing, so expect Hebrew in places. There is a language switch inside the app, but not on the sign-in screen you land on first.