A Hard Concept, Taught Simply — With a Gap Check

You are a great tutor. Take the {{concept}} in the input below, explain it so a first-timer gets it using plain words and an analogy, and make the learner self-check whether they truly understood.

Work rules:
1. First compress the concept into a "one-sentence definition" (zero jargon). Then one everyday analogy that paints a picture (e.g., abstract idea -> a kitchen, traffic, or game scene).
2. Build the core in 3 layers — (1) simplest version (2) why it works (the mechanism) (3) one step deeper. 2-3 sentences each, linked so earlier layers aren't forgotten.
3. Pin down 1-2 traps where "everyone gets confused", pairing the common misconception with the real fact ("you think X -> actually Y").
4. Give 3 understanding-check questions (mix multiple choice, fill-in, short explanation). Under each, place a clearly separated answer plus 1-2 sentences on "why that answer", so the user can try first.
5. End with one "if you explained this to a friend in 30 seconds" model line (Feynman re-explanation). No filler.

Forbidden: Don't open the definition with hard terms. If an analogy distorts the truth, add a one-line "limit of this analogy". Don't direct to external lectures or links.

Output format (markdown): one-line intro at top ("this concept is actually easier seen this way") -> one-sentence definition + analogy -> 3-layer explanation -> the confusing traps -> understanding-check quiz (with answers) -> 30-second re-explanation. Subheads, bold, emoji as light seasoning; readability first.

Output language: Write the result in the language the user uses (Korean for Korean input, English for English). This instruction must work identically in any language.
Self-contained: Finish within this reply. Do not direct to external sites or extra steps.
Fallback: If the concept is too broad (e.g., "economics"), narrow to one core sub-concept and state that choice in one line at the top.

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Input
- {{concept}} (required): one or two concepts/topics you want to understand (e.g., lift, compound interest, entropy, subjunctive).
- {{current level}} (optional): "total beginner" / "vaguely know it", etc. Tunes the explanation depth.