Feynman Eli5

Feynman Technique / ELI5 Layered Explanation

Explain a concept the way Richard Feynman recommended teaching: force genuine simplicity first, then rebuild precision layer by layer. The core mechanic is that writing the ELI5 version exposes exactly which parts of your own understanding are fuzzy — so the layering is not just a presentation style, it's a comprehension check.

When to use this skill

• User says "ELI5", "explain like I'm 5", "Feynman style", "explain simply", "in plain English", "dumb it down"
• User is clearly struggling with a concept after a more technical explanation didn't land
• Proactively for concepts that are notoriously hard to build intuition for even among practitioners: recursion, closures, gradient descent, Bayesian inference, dependency injection, monads, CAP theorem, eigenvectors, etc. — even if the user just asked "explain X"

Language

Always respond in the same language the user is writing in — do not default to English. Detect the language from the user's most recent message and write the entire explanation (headers, analogies, self-test question, everything) in that language. If the user switches languages mid-conversation, switch with them on the next response. Code and code comments may stay in English regardless of the surrounding language, following normal programming convention, unless the user explicitly asks for translated code comments.

Structure (always four layers, in this order)

Layer 1 — Explain like a child

• Use a physical, everyday analogy. No jargon, no technical terms at all. If you catch yourself writing a term from the domain, replace it with the analogy's vocabulary instead.
• 2-4 sentences. This layer must stand alone and make sense to someone with zero background.
• Good analogies come from: household objects, cooking, games, physical spaces, animals, everyday social situations. Pick one that maps cleanly onto the actual structure of the concept — don't force a cute analogy that breaks down under scrutiny.

Layer 2 — Add real terminology

• Reintroduce the actual technical vocabulary, explicitly mapping each term back to the Layer 1 analogy ("in code, the 'slot' from Layer 1 is called an interface").
• Include one small, concrete code example or worked mini-example if the topic is technical.

Layer 3 — The "why does this matter" layer

• This is the layer most explanations skip, and it's the one that actually builds tacit knowledge. Answer: what breaks or becomes painful WITHOUT this concept? Show the failure mode concretely (a bad-code example, a wrong intuition, a real consequence) before showing how the concept fixes it.
• This layer should contain the most "aha" — it's where surface knowledge turns into judgment about when/why to use the thing.

Layer 4 — The subtlety that trips people up

• Name ONE specific misconception or edge case that people coming from a different background (a different language, a different field, a naive first read) commonly get wrong. Be concrete about who gets confused and why — this is often the most valuable layer for someone who already has partial knowledge.

Close — self-test

• End with exactly one question that requires the user to reconstruct the core reasoning in their own words — not a recall question ("what is X called") but a reasoning question ("why should Y not do Z itself, but instead receive it from outside").
• Include a one-line hint about what a correct answer must reference, so the user can self-check without being handed the answer outright.
• Do not answer this question yourself. End the response here.

Formatting

• Use ## Layer 1: ... style headers, translated into the user's language per the Language section above (e.g. "Lớp 1" in Vietnamese, "Capa 1" in Spanish).
• Keep code blocks minimal and focused — one small example per layer max, not a full program.
• Total length: proportional to concept complexity, but default to concise. This is meant to be read in one sitting, not skimmed.

What NOT to do

• Don't skip straight to Layer 2 vocabulary in Layer 1 "for clarity" — the whole point is forcing a jargon-free pass first.
• Don't answer the self-test question in the same response.
• Don't pad Layer 4 with a generic "it depends" — name a specific, real misconception.
• If the user pushes back that a layer is "too simple", that's the technique working as intended, not a flaw to fix — explain briefly why the simple layer exists rather than cutting it.