Sage

You do not know a thing until you can teach it. Sage gives you someone to teach.

Client: Personal project
Where: Built while studying
Year: 2026
Work: Design and build
Live: sage-app-delta-brown.vercel.app

The idea

The Feynman technique says that if you cannot explain a concept in plain language, you have not learned it. The problem is that it needs a listener, and a listener who asks the right questions.

Sage is that listener. You explain a concept to Pip, and Pip asks you the question your explanation left open. Not a quiz. The specific gap in what you just said.

A real session. The student explains motor unit recruitment and the size principle. Pip answers: "You said the small units are slow twitch and fatigue resistant. What is it about their physiology that actually makes them resistant to fatigue compared to the large units?" The blackboard behind Pip collects the key terms from the explanation. — A real session on motor unit recruitment. The explanation covered the size principle and stopped there, so that is exactly where Pip pushed.

How a session runs

You pick the topic and how hard it should be: Student mode has you teach the concept. Adversarial plants mistakes for you to catch. Quick check is three recall questions. Same topic, three different kinds of pressure.
You can talk instead of type: The session is voice first, because saying a thing out loud is closer to teaching it than writing it. Typing is there for the library and the bus.
The follow-up comes from your words: Pip quotes the phrase you used and asks what is underneath it. The blackboard fills with the terms you actually said, so you can see what your explanation leaned on.
Weak spots come back: Each session is scored and scheduled. A concept you explained badly returns sooner than one you explained well, so the gaps surface instead of hiding behind the topics you enjoy.

The Sage session setup on a phone: a topic field reading "Motor unit recruitment", and three session modes to choose from: Student Mode, Adversarial, and Quick Check. — setting it up

The same session on a phone, showing the explanation and Pip's follow-up question about what makes slow twitch fibres resistant to fatigue. — mid session

Set the topic, pick how hard Pip should be, then explain. It runs the same on a phone as on a laptop.

Built with

React and TypeScript on the front, Supabase for accounts and progress. It tracks what you have explained well and what you keep skipping past.

Sessions are scored and scheduled to come back. A concept you explained badly returns sooner than one you explained well, so the weak spots surface instead of hiding behind the topics you enjoy.