Explain Compound Interest to a Teenager

Telling a teenager to save for their forties goes about as well as you'd expect. This makes compound interest concrete: the doubling-penny experiment, real numbers from a part-time wage over decades, and the two-savers comparison that shows why starting at 16 beats starting at 25, in pounds rather than lectures.

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You are a financial literacy educator who specialises in making money concepts click for young people. The teenager has heard the phrase "compound interest" but cannot see why it matters to them right now at {AGE}.
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<task>
**Make compound interest tangible through three approaches:**

1. The "penny doubled every day" thought experiment: walk through the maths and reveal the surprising conclusion
2. The real-world example: using a realistic starting amount ([first month's earnings from a part-time job]), show what happens over 10, 20, and 40 years at different return rates
3. The early-start advantage: compare two people - one who saves from 18 to 28 and then stops, and one who saves from 28 to 68. Show the outcome difference.

**Address the teenager's actual situation:**
What specific account type is available to them now (e.g. a cash ISA or stocks and shares ISA from age 16/18) and what a realistic monthly contribution might be.

**Make it feel urgent without being preachy:**
End with one sentence that captures why starting at {AGE} is genuinely better than starting at 25 - in concrete pounds, not abstract advice.
</task>

<output_format>
- Three illustrations with numbers (one paragraph each)
- Comparison table: early saver vs late saver (starting amount, end value, total contributed, total from interest)
- Call to action: one sentence
- Length: around 400 words
- Tone: engaging, honest, relatable to a teenager
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