Lesson 0004 · Exercise

One decision

No new material. Three lessons, one decision, played through step by step. Each wrong turn here is you forgetting something you already met — the feedback will tell you which.

Past patients: symptoms in, known outcome out. A new patient arrives. Build the system that decides whether to flag them for follow-up testing — from the shape of a correct answer, all the way to whether the deployed rule lands the same way on everyone. The options at each step are unlabeled on purpose. Some are real mistakes drawn from the last three lessons, not arbitrary wrong answers — if one goes wrong, you'll see exactly which principle you lost sight of.

This is the last lesson from this deck. If a fallacy tag above felt like a stretch rather than a real echo of the lesson it points back to, that's exactly the kind of thing worth telling me — the whole point was that each one should genuinely be the same mistake in a new setting, not a label pasted on.