Explain Like Im 5

---
name: explain-like-im-5
description: Explain any topic from first principles, in words a five-year-old could follow. Dig down to bedrock facts the reader already knows from everyday life, then build back up one idea at a time, with an everyday picture for each idea, where that picture breaks, why it has to be so, and a tiny check question. Use when someone asks to "explain like I'm 5", "ELI5", "teach me from scratch", "from first principles", "I don't get it", or wants to understand why something works rather than just what it is.
---

# Explain like I'm 5, from first principles

The goal is not a cute summary. It is that the reader understands **why** the thing works, well
enough to rebuild the idea on their own, starting from things they already know to be true.

Two moves do the work: **dig down** until you reach bedrock, then **build up** one rung at a time,
using nothing the reader hasn't already been given.

## 1. Dig down

1. **Name the question.** Rewrite the topic as one plain question a child would ask.
   "GPS" becomes "How does my phone know where I am?"
2. **Ask what has to be true.** For the thing to work, what must be true? Then ask the same of
   each answer, until every branch ends in bedrock.
3. **Stop at bedrock.** Bedrock is something a five-year-old already knows from their own body
   and their own day: things fall when you let go; a push makes things move; a hot drink cools
   down; you can count apples; the far side of the playground takes longer to run to.
   These are **not** bedrock:
   - a fact that is true only because a grown-up said so ("electrons are negative");
   - a name ("photosynthesis", "inflation", "a neural network");
   - a formula.
4. **Throw out the borrowed parts.** The usual explanation hides steps inside big words ("it uses
   satellites", "the market sets the price"). List those hand-waves and refuse to use them until
   you have built them.
5. **Order the ladder.** Put the ideas in an order where each rung uses only bedrock and the rungs
   below it. Aim for 3 to 8 rungs. If a rung needs two new ideas, split it. If two rungs say the
   same thing, merge them.

## 2. Build up

Teach the rungs bottom to top. Every rung follows these rules:

- **One new idea per rung.** If you notice you are explaining a second one, it needs a rung of
  its own.
- **Short sentences and everyday words.** Most sentences under 15 words.
- **Explain first, name second.** Use a new word only after the idea it names is in place, then
  hand over the word: "Grown-ups call this *latency*."
- **One picture from a child's world**: the kitchen, the bath, a playground, toys, a queue at
  school. The picture must do the same work as the real thing, not just look like it.
- **Say where the picture breaks.** Every analogy is wrong somewhere. Name the spot, so the
  reader doesn't carry the wrong part forward.
- **Say why it has to be this way**, not just that it is. "If it were any other way, then …"
- **End with one tiny check question** the reader can answer from this rung alone, with the
  answer right after it.

Then climb back to the question, and answer it in three to five sentences that use only words
from the ladder.

## Honest simplifying

- Simplify by **leaving things out**, never by saying something false. If a simplification would
  turn false at the next level, mark it: *(First-step picture. The fuller story: …)*
- Use small, real numbers a child can picture, and say when a number is an estimate.
- If you are not sure a fact is right, say so instead of smoothing it over.
- Simple words are not baby talk. Don't write "great question!", don't put a cheerful exclamation
  mark on everything, and don't write "simply", "just" or "obviously": they tell the reader they
  should already know.

## If the reader is not five

If the request or the team's Brief says who the learner is ("I know high-school algebra", "I'm a
nurse"), raise the bedrock to what they already know and skip the rungs below it. Keep the method
and the honesty; change only where the ladder starts.

## If you were handed a ladder

In a team, an earlier step may already have dug down and the learner may have answered it. Teach
that ladder, in that order, and honour what the learner said (skip what they know, start where
they asked). If a rung is wrong or out of order, say so at the top before you teach, rather than
fixing it quietly.

## The shape of the answer

```markdown
# <the question, in a child's words>

**The short answer:** two sentences a reader could stop at and still be right.

## What you already know
- <bedrock fact>, one line each, three to five of them

## The ladder

### 1. <the rung's idea, as one short claim>
<the explanation>

**Picture it:** <the everyday picture>
**Where the picture breaks:** <where it stops being true>
**Why it has to be so:** <the reason>
**Check:** <a tiny question> *Answer:* <the answer>

### 2. …

## Back to the question
<three to five sentences, using only words from the ladder>

## Words you earned
- **<term>**: what it means, in ladder words

## Where to go next
- <two or three next questions, each one rung higher>
```

## Before you hand it back

- [ ] Every word a child wouldn't know is explained before it's used, or listed under
      "Words you earned".
- [ ] Each rung uses only bedrock and the rungs below it.
- [ ] Every picture has a "Where the picture breaks" line.
- [ ] Nothing taught is false, and every simplification that would turn false later is marked.
- [ ] Someone who reads only "The short answer" still comes away right.