# Introduction

> learn.ninja turns anything you give your agent into one short, interactive lesson you can share as a link.

learn.ninja is a skill for your AI agent. Give the agent a topic, an article, notes, docs, a meeting transcript, or some code, and it writes **one short lesson** about the central idea, checks it, and publishes it. You get a link that anyone can open and play in the browser, on a phone or a laptop.

A lesson takes 5 to 10 minutes. It isn't a summary to read: it's a run of small screens called **bricks**, where you guess, practise, and get feedback on every answer. Try one:

```json
{
  "id": "p1",
  "prompt": "$1,000 at 5% a year, compounded yearly. How much after 2 years?",
  "hint": "Work out year 1 first, then use that as the new starting amount.",
  "explanation": "Year 1: $1,000 × 1.05 = $1,050. Year 2: $1,050 × 1.05 = $1,102.50.",
  "type": "choice",
  "options": [
    {
      "id": "a",
      "text": "$1,102.50"
    },
    {
      "id": "b",
      "text": "$1,100.00",
      "feedback": "That's simple interest. Year 2 also earns interest on year 1's $50."
    },
    {
      "id": "c",
      "text": "$1,050.00",
      "feedback": "That's after 1 year. Apply the 5% growth once more."
    },
    {
      "id": "d",
      "text": "$1,010.00",
      "feedback": "That's 0.5% a year. 5% is 0.05, so multiply by 1.05."
    }
  ],
  "correct": [
    "a"
  ],
  "multiple": false
}
```

## How it works

1. **Install the skill** in your agent with one command. See [Install the skill](https://learn.ninja/docs/install).
2. **Ask for a lesson**: "Make me a lesson from this article", or "Teach me how `map` differs from `forEach`".
3. **Share the link.** The agent replies with a link like `learn.ninja/l/how-compound-interest-works-k3x9a2mq`.

To change the lesson, just ask: "make it harder", "add a question about fees". The agent republishes to the same link.

## What it costs

Nothing. learn.ninja is free, and there's no account to create.

## Good to know

* Links last **24 hours** for now. Ask your agent to publish again for a fresh link.
* Lessons can be in any language, including right-to-left languages like Arabic.
* Lessons never run code. Visuals are plain HTML shown in a sandbox.