The Feynman Technique

Learning and teaching method: understanding is tested by whether you can explain the concept simply. Named for richard feynman; his Caltech colleagues called him “the great explainer”.

The loop

1. Say what you know in PLAIN language, as if to a bright 12-year-old. No jargon until the idea lands.
2. Find the gap — where the plain explanation stumbles is exactly where understanding is missing. Return to the source for just that piece.
3. Simplify and use analogy. If the explanation needs the technical term to survive, it isn’t understood yet.
4. Test by teaching: have the learner explain it back or predict an outcome (“what does this print?”). Their gap is the next lesson. Iterate.

Why it works

Jargon can hide a hole; plain language can’t. Feynman’s Brazilian-physics-students story: they could recite definitions but not apply them — names without the thing.

Application to AI Systems & Evals

When evaluating agent understanding and reasoning capabilities, plain-language decomposition exposes latent gaps in system prompts and test rubrics. Complemented by build from scratch pedagogy for deep technical topics where building a toy prototype makes understanding executable.

Related

first principles thinking, build from scratch pedagogy, richard feynman, andrej karpathy.