Five children. Each has a hidden learning level and a hidden misconception. You get six turns. You teach blind — then the X-ray turns on and you see what you walked past.
Needed because the class is generated live. A six-turn lesson plus the coaching report costs roughly $0.05–0.15 on Claude Sonnet 5.
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The lesson is replayed above with what each child was actually thinking — the thing a real teacher never gets to see.