The mastery engine running on real Unit 1 items from the HS Chemistry build. Answer as a student would — or let a simulated student answer — and watch how each response moves the knowledge estimate and how many questions mastery actually takes.
Policy: certify at evidence P(L) ≥ 0.95 (no transit credit — proof only), floor 3 items on MCQ-only gates else 2, quant atoms need ≥ 1 numeric correct (numeric served first); where an atom\u2019s items span ≥ 2 facets (e.g. milli/centi/kilo), certifying evidence must cover 2 of them and unseen facets are served first; route to lesson at pacing P(L) < 0.40 only after ≥ 1 incorrect; cap 10 items → escalate to re-teach. Parameters: MCQ guess 0.25 / slip 0.10 · numeric guess 0.03 / slip 0.12 · transit per atom kind. Items are served gate-items-first; production/drawing tasks are in the real bank but can't be auto-scored here.