Pre-class preparation (15 min async) Bring one analysis you have run, in whatever state it is in. It does not need to be tidy; untidy is more useful here. Read Technical Unit 04, section 2, on materialization versions and root-ID instability. Minute-by-minute plan 00:00-06:00 | Framing: the silent bug Prompt: "Your notebook ran fine last month and gives a different number today. Nothing in your code changed. What happened?" Establish that analysis against an unpinned segmentation is the most common silent correctness failure in this field. 06:00-16:00 | The five-element checklist, modeled Instructor walks one real analysis through: dataset release ID, materialization number, code commit hash, environment specification, parameter configuration. Show what breaks when each one is missing, in turn. 16:00-30:00 | Guided practice: audit your own work Learners score their brought-in analysis against the five elements. Most will fail two or three; say so in advance to make that safe. Produce a remediation list ordered by how cheap each fix is. 30:00-40:00 | Clean-environment rerun Attempt a rerun of a partner's analysis from their instructions alone, without asking them questions. Log every point of friction. The friction log is the deliverable, not the successful rerun. 40:00-50:00 | Known limitations, written honestly Each learner drafts a limitations paragraph naming concrete failure modes, excluded samples, and failed runs — not generic caveats. Discuss why this is a hidden-curriculum norm: reviewers expect it, and almost nobody is taught to write it. 50:00-57:00 | Competency check Submit: completed five-element record, friction report on a partner's package, and one limitations paragraph. 57:00-60:00 | Exit ticket "One thing in my current work that another person could not reproduce today." Formative checkpoints At 30 minutes: every learner has identified at least one missing element in their own work. A learner reporting five out of five has probably not audited honestly — check. At 50 minutes: limitations paragraphs name specific failure modes rather than generic hedges.