The Misconception Museum

The course kept a museum of canonical errors — each one numbered beside its correct twin — and walking the whole gallery at once shows the errors share a shape: a true thing, stretched one step too far.

Begin at the entrance, with the course's first exhibit: computer science is programming (0002) — true that programming lives inside it, false as the boundary. Then the hall of meanings: the bits contain the meaning (0239) — bits are real, meaning lives in the declared type; the model is the world (0121) — the model is genuinely useful, which is exactly why forgetting its erasures is dangerous. The measurement wing: Big-O is a stopwatch (0129) — growth confused with clock time; greedy finds the best (0139) — a real method's local wins mistaken for a guarantee; NP means not polynomial (0163) — a name misread as an antonym. The machine room: the computer runs my code (0182) — smooth translation mistaken for no translation; my app talks to the hardware (0293) — smooth mediation mistaken for no mediator; memory keeps it when the power dies (0260) — one layer's contract assigned to another. The engineering annex: the cast is free (0366) — a legal operation mistaken for a harmless one; ACID costs nothing (0426's twin) — guarantees mistaken for gifts; refactoring rewrites behavior (0485) — a safety word stretched over feature work. And the civic wing: free means gratis (0493), every infection is a virus (0620), the type is the structure (0096). Fifteen exhibits, one pattern: each error is a truth that stopped one unit too early. The twins exist because the errors are canonical — predictable, teachable, and worth a number of their own.