# Assessment Instructions: Problem Set 01 — ISM Phases and Pressure Balance

## Inputs to Inspect
Student submission, this problem set, the solution key, the corresponding lecture slides/notes, and the referenced dataset(s) under `materials/ASTR360/data/`.

## Grading Standard
Award credit for correct method and units first, then for the specific numeric result. A student who shows correct reasoning with a small arithmetic slip should receive most of the available credit; a student with a correct-looking number but no visible derivation steps should not. Because this is a 300-level quantitative interstellar-medium course, full marks require a genuine derivation wherever the problem set asks for one, and a genuinely reasoned (not merely asserted) interpretation wherever the problem asks for scientific judgment (e.g., honestly characterizing an idealized model's disagreement with a real object).

## Problem-Level Criteria
- Problem 1: verify correct P/k arithmetic and a reasoned (not just numeric) equilibrium comparison to CNM/WNM.
- Problem 2: verify the student explains the large H II/WNM pressure mismatch physically rather than treating it as a framework failure.
- Problem 3: verify correct algebraic solve for temperature given a fixed pressure and density.
- Problem 4: verify the student does not overclaim the filling-factor sum is or should be exactly 1.

## Resubmission Policy
Students may resubmit within one week of receiving feedback. A resubmission must show a corrected derivation, not only a corrected final number, and should reference the specific feedback comment it addresses. Regrade to a maximum of 90% of the original point value unless the error was a grading mistake.

## Common Errors to Flag
- Confusing pressure ratio direction (stating phase A is "N times lower pressure" when it is actually higher).
- Treating the H II region's pressure mismatch with the WNM as an error in the pressure-balance framework rather than expected transience.
- Unit errors in P/k arithmetic (cm^-3 K is the conventional unit; watch for missing or extra factors).