HFT at BEA 2026 Shared Task 2: Blunt-Edge Models for Hybrid Grading
Paper · 2026 · Ulrike Pado
Summary
The paper addresses automatic grading of German short answers in the BEA 2026 Shared Task 2. It deliberately builds a low-cost, replicable "blunt-edge" grader rather than an optimized system. Seven open-source LLMs hosted by GWDG Göttingen (e.g., gpt-oss-120b, Llama-3.3-70B-Instruct, Qwen3, Mistral-Large-3, Gemma-3, SauerkrautLM) were each tested with four German zero-shot prompts of increasing complexity. On their own, these graders are mediocre. They reach about 0.48 QWK, are competitive in the Unseen Question track, and rank last in the Unseen Answer track.
The author then simulates a hybrid workflow:
- The model's more precise class ("Incorrect") is accepted without review.
- Answers predicted "Correct" go to human review.
This approach cuts manual effort substantially while matching or beating cutting-edge systems, especially when little task information is available. The work matters for practical use for three reasons:
- It keeps a human in the loop, which is relevant under the EU AI Act.
- It protects data privacy by relying on open-source models.
- It shows teachers recurring patterns in student answers.
The main caveat is that the remaining errors fall entirely on students wrongly marked incorrect.
Key points
- Setup. Seven models were run at temperature 0.01 through RAGAS. They were tested with four prompts: Baseline, Fan et al., Role, and a committee-of-experts prompt from Wang et al.
- Prompt and model results. Simpler prompts that add a little context worked best. The Wang et al. prompt sharply hurt some models. The top trial score was Llama with the Fan et al. prompt (0.4927 QWK).
- Test results. GPT-OSS with the Fan et al. prompt kept about 0.48 QWK, placing 5th of 9 in the 2-way Unseen Question task and last in Unseen Answer.
- Rubric coverage. Adding the "Partially Correct" rubrics, counted as Incorrect, raised QWK by about 0.03 across all configurations.
- Hybrid simulation. On 7072 training answers, 5103 "Incorrect" predictions were accepted and 1969 were reviewed, cutting human workload by 71%.
- If human review is perfect, overall error is 12% and weighted F1 is 0.896.
- If reviewers err on 15% of the answers they check, F1 is 0.828, which would rank 1st in Unseen Questions and 8th in Unseen Answers.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 works
Cite
Cite as Ulrike Pado. 2026. HFT at BEA 2026 Shared Task 2: Blunt-Edge Models for Hybrid Grading. Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026).
@inproceedings{pado2026hft,
title = {{HFT at BEA 2026 Shared Task 2: Blunt-Edge Models for Hybrid Grading}},
author = {Ulrike Pado},
booktitle = {Proceedings of the 21st Workshop on Innovative Use of NLP for Building Educational Applications (BEA 2026)},
year = {2026},
doi = {10.18653/v1/2026.bea-1.86},
url = {https://doi.org/10.18653/v1/2026.bea-1.86}
}References
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