Rubric — Assignment 6 (20 marks)

Applies to Assignment 6. Band descriptors per criterion; award half-bands where genuinely between.

Part 1 — Portfolio pages (8; ~2.7 per page, mark holistically)

Band	Descriptor
8	Three pages from three distinct blocks; each names three ordered moves with reasons for the order; each generalisation carries a genuine counter-example (a problem where the move misfires); the trace solves the worked instance correctly by method.
6–7	Pages complete but one order-justification is circular ("first I read the problem, then I solve it"), or one counter-example is a token denial rather than a real misfire case.
3–5	Moves listed without ordering reasons, or counter-examples missing on two pages, or traces copied from the case's published solution wording.
0–2	Summaries of the cases rather than a personal method; no distinct-block coverage.

Part 2 — Adversarial review (4)

Band	Descriptor
4	Three concrete challenges (each names a move or an input); each accept/rebut sentence engages the specific challenge — a rebuttal argues why the misfire does not apply, an acceptance names the corrected move.
2–3	Challenges present but generic ("your move might not always work"), or one accept/rebut missing.
0–1	Praise instead of challenge; partner unnamed.

Part 3 — Unifying program (8)

Criterion	Band	Descriptor
(i) Invariant loop	2	Invariant stated in the paragraph and true of the code; 1 if stated but false, or true but unstated.
(ii) Decomposition	2	≥ 3 functions, each with a one-line contract (parameters, return, no prints-as-returns); 1 for ≥ 3 functions with vague contracts.
(iii) Test table	2	≥ 6 rows including one deliberate-failure row with the failure demonstrated (before the fix) or explained; 1 for a happy-path-only table.
(iv) Mapping paragraph	2	Each program part explicitly tied to a portfolio page's method; 1 for a vague "this shows my method" sentence.
Program quality	—	Not separately marked, but a program that does not run caps Part 3 at 4.

Cross-cutting modifiers

+1 (max 20): a portfolio page that connects two blocks' methods (e.g. how Block I's assumption-stating changes Block III's invariant work) with a concrete example.
−1: any portfolio page whose trace matches the published case solution's numbers and phrasing — the closed-book trace is the honesty check.
−1: the Part 3 problem is a restated course case (cs-013's sentinel echo, cs-049's word tally, etc.) rather than the student's own.