--- pretty_name: Introduction to AI (Stage 2) Practical Exam — Submissions and Dual TA Grades license: cc-by-nc-4.0 task_categories: - text-classification - text-generation language: - en tags: - education - automated-grading - llm-evaluation - prompt-sensitivity - code-assessment size_categories: - 1K/Q{1,2,3}.ipynb` | the anonymized student notebooks | | `Solutions/` | instructor reference solution per question | | `stage_2_rubrics_ta.md` | the marking scheme the TAs graded against | | `few_shot_examples.json` | two worked examples per question for the few-shot runs (IG18, IA201): student code with the IG08 model's (`gemini-3.1-pro-preview`) score, bonus and reasoning, not TA marks | Students are identified only by a number (1–1038) that is stable across every file. Notebook `submissions_extracted/2/Q2.ipynb` belongs to the student in row `Number == 2` of the grades CSV. ## The exam and its scale Three questions: **Q1** tabular regression (predict food delivery time), **Q2** PyTorch (predict age from face images), **Q3** classification (find the most predictive feature in an anonymized dataset). Marks come from the rubric's task tables, not its header totals — the two disagree in the distributed PDF, which is preserved here as `stage_2_rubrics_ta.md`: | question | base | bonus | |---|---|---| | Q1 Regression | 23 | 3 | | Q2 PyTorch | 14 | 3 | | Q3 Classification | 19 | 3 | Two instructor corrections were issued by email *during* grading, both affecting Q3 only (Part 1 dropped a task and became 2 marks; Part 4 dropped a task and became 5). Both are folded into the rubric file and marked ⚠. ## Ground truth quality Every student is graded by two TAs, so the dataset carries its own noise floor: | statistic | value | |---|---| | **floor: TA-vs-TA mean absolute difference (totals)** | **5.13** (95% bootstrap CI 4.80–5.48) | | inter-TA correlation (totals) | 0.871 | The floor is ~8% of the ~65-point scale. An AI grader's mean absolute error against the TA average is read against 5.13, the distance between the two TAs, not against zero. ## Anonymization Student names, ID numbers, emails, and submission links are absent. Notebooks were rebuilt from scratch keeping only code cells: markdown cells, outputs, execution counts, and all per-cell metadata were dropped, so Colab `executionInfo` blocks (which embed a Google account name and user id) do not survive. Remaining identifiers inside code — names in variable names or comments, emails, ID numbers, phone numbers, filesystem usernames — were replaced with `ANON` (identifier-safe) or `[REDACTED]`. One identifier is kept on purpose: the exam-data download line in the notebooks, the solutions and `few_shot_examples.json` names the course's Kaggle dataset (its owner's handle and the `q{1,2,3}-ka-ai-2026` slugs), because that is the text the published runs graded. Scrubbing was verified two ways: an exhaustive scan against the full roster (every student and TA name, email and ID, plus generic email/ID/phone patterns and notebook-format regressions), and an LLM review of all ~25k comment and string literals looking for identifiers the roster could not know about. The second pass is what caught a reference to an instructor by first name and one student who had loaded the exam data from a personal account. TAs appear only as pseudonyms (`TA_1`, `TA_2`, …). One slot carries the composite id `TA_49+TA_50`: two TAs share that slot, which covers 18 students. The pseudonym-to-person mapping is **not** published, so grading behaviour cannot be attributed to any individual. The grader in the project repository is the script that produced the published runs, prompt included, and the notebooks here are the ones it graded. ## Known gaps, stated plainly - 24 students from the original cohort are absent: they uploaded nothing, an unreadable archive, or files that were not the exam. The remaining 1,038 are numbered contiguously. - 75 students are missing a notebook for at least one question (96 notebooks in all: 4 for Q1, 44 for Q2, 48 for Q3) — they did not submit that question. An absent `Q.ipynb` means exactly that, and the grading code scores it 0. - The rubric's header totals contradict its own task tables in all three questions. This is preserved rather than corrected; it is part of what a real grading prompt has to cope with. - 29 TA per-question grades (on 27 students) exceed the question's maximum including bonus (Q1 26, Q2 17, Q3 22), and one TA total (68.45) exceeds 65. - Two TA grades awarded credit for a question the student never submitted (8.0 and 10.0, each contradicted by the paired TA's 0). Both were set to 0 and the totals recomputed: ground truth that credits work no grader can see would penalise every grader, human or machine. - Nine rows record 0.0 for exactly one TA while the paired TA awarded real marks: ungraded slots stored as zeros. They are kept; without them the floor is 5.09 (95% CI 4.76–5.42) instead of 5.13, and no conclusion in the paper changes. A further nine rows carry 0.0 from both TAs: their notebooks are the blank exam template or nearly so, so these are genuine zero-mark papers, not recording errors. ## The LLM runs The paper grades this exam with 162 configurations: 132 over 17 open-weights models and 30 with closed models (23 Gemini, 6 OpenAI, 1 Anthropic), one workbook per configuration in the project repository's `introduction_to_ai_results/results/`, holding the AI score, bonus and reasoning per question alongside the TA columns. The core comparison runs every open-weights model twice over the full cohort with an identical prompt except for its leading persona preamble: - **neutral** — "You are a strict but fair teaching assistant." - **strict** — "You are a HARSH teaching assistant. Award the MINIMUM defensible score for any task that is incomplete, buggy, or deviates from the rubric. Never give partial credit if the task does not run correctly." Everything else is held fixed: reference solution included, per-task breakdown requested, no chain-of-thought, temperature 0, one sample per question. The other personas are `STRICTNESS_PRESETS` in `introduction_to_ai_grade_with_local.py`, and `build_prompt()` in the same file assembles the full prompt around them. `behaviour` classes: `refusal` (≥90% of students zeroed, awarded-total std < 0.5), `near-refusal` (≥90% zeroed but still varying), `collapse` (MAE ≥ 15.7, i.e. 3.07× this exam's floor, the multiple the Computer Vision exam's MAE ≥ 8 fixes, while still discriminating between students), `graded` otherwise. ## Reproducing The grading and analysis code lives in the project repository, which expects this folder at `introduction_to_ai_dataset/` beside it: ```bash # serve a model with vLLM, then: python introduction_to_ai_grade_with_local.py --all \ --model --api-base http://localhost:8000/v1 \ --max-output-tokens 8192 \ --with-solution --no-reasoning --with-breakdown \ --strictness strict --temperature 0.0 --runs 1 \ --tag IA02_m-_sol1_gd0_rs0_bd1_str-strict_t00_n1 python analysis/introduction_to_ai_run_analysis.py # MAE, CI, behaviour class per run ``` `introduction_to_ai_submit_persona_sweep.sbatch` is the SLURM launcher: an array job, one task per persona (`--array=0,1` gives the neutral+strict pair). `STUDENTS=1-5` turns it into a smoke run that writes to `introduction_to_ai_results/smoke/` instead of `results/` and leaves the run tracker alone. Never point two runs at one output workbook — the grader holds the whole workbook in memory and rewrites it after every question, so two writers silently destroy each other's grades. The published runs used vLLM 0.19.1. Grading is not bitwise reproducible: generation is unconstrained, and JSON is parsed leniently. ## Licence and intended use Released under **CC BY-NC 4.0** ([Creative Commons Attribution-NonCommercial 4.0 International](https://creativecommons.org/licenses/by-nc/4.0/)): use, share and adapt it for non-commercial purposes with credit to the source. The student work was contributed with the course instructors' permission and is released for research on automated grading. Do not attempt to re-identify students or TAs. ## Citation ```bibtex @misc{habibullah2026llmgraderssucceedbreak, title={Where LLM Graders Succeed and Break: Evidence from Two Computer-Science Exams}, author={Ali Habibullah and Yazan Alshoibi and Mohammad Alshiekh and Salman Khan and Naeemullah Khan}, year={2026}, eprint={2609.29333}, archivePrefix={arXiv}, primaryClass={cs.CL}, url={https://arxiv.org/abs/2609.29333}, } ```