Prompt: Explain a Complex Topic Simply

You are a teacher who is honest about where an analogy stops being accurate.

Objective: Explain {{TOPIC}} to someone with {{BACKGROUND — e.g. no technical background, a high-school level of maths}}.

Context: They're trying to understand this because {{WHY THEY NEED TO KNOW THIS — e.g. deciding whether to invest, making sense of a diagnosis}}.

Constraints:
- Use one concrete analogy, and explicitly say where the analogy breaks down
- Do not use jargon without immediately explaining it in plain terms
- Include one worked example, not just an abstract description
- Keep the whole explanation under 300 words

Output format: Return the explanation as plain prose, with the analogy's limitation as a final short paragraph.

Before finishing, check that the analogy used doesn't imply something false about the topic that could mislead the reader.

TOPIC: how compound interest works
BACKGROUND — e.g. no technical background, a high-school level of maths: no technical background
WHY THEY NEED TO KNOW THIS — e.g. deciding whether to invest, making sense of a diagnosis: deciding whether to pay off a credit card faster or invest the spare money instead

Compound interest is like a snowball rolling downhill: it starts small, but as it rolls it picks up more snow, and the bigger it gets, the more it picks up with each turn. Your starting amount is the snowball, and the "snow" is interest — each period you earn interest not just on your original amount but also on the interest already earned, so growth speeds up over time instead of staying flat.

Worked example: put £1,000 in an account paying 5% a year. After year one you have £1,050. In year two, that 5% is calculated on £1,050, not the original £1,000, giving £1,102.50 — £2.50 more than a flat 5% on £1,000 would earn. Over many years that extra layer compounds noticeably. The same maths works against you on debt: interest on an unpaid credit card balance compounds in exactly the same way.

Where the snowball analogy breaks down: a real snowball's growth is limited by how much snow is on the ground, but compound interest has no built-in ceiling — it keeps compounding for as long as the money stays in and the rate holds, which is why starting early matters more than the analogy alone suggests.

Why the basic version fails

“Explain X like I’m five” often produces a tidy analogy that’s memorable and quietly wrong in an important way, because nothing in the request asks the model to check whether the analogy actually holds up.

What this prompt fixes

Requiring the model to state where its own analogy breaks down turns a comforting oversimplification into something more honest and more useful for someone who’ll act on the explanation. The worked example gives something concrete to check the explanation against.

Tips per model

• Claude is generally good at flagging its own analogy’s limits without much prompting, but the explicit constraint makes it consistent.
• Gemini and ChatGPT both produce vivid analogies — the “where it breaks down” check is what stops a vivid analogy from being a misleading one.
• If the explanation still feels too abstract, name the exact decision the reader is trying to make in the “why they need to know this” field — a concrete stake produces a more concrete worked example.