When the Strongest Teacher Is Not the Best Teacher: Student-Centric Answer Selection

Zhengyu Hu, Zheyuan Xiao, Linxin Song, Fengqing Jiang, Yuetai Li, Zhihan Xiong, Junhao Lin, Yue Liu, Yao Su, Lijie Hu, Kaize Ding, Teng Xiao, Radha Poovendran


Abstract
LLM training increasingly relies on teacher-generated supervision, from synthetic responses to reasoning traces and tool-use demonstrations. Current practice often chooses the highest-performing teacher to generate student training data, implicitly treating teacher test performance as a proxy for teaching quality. We show that this assumption can fail: even when multiple teachers provide correct answers to the same question, the answer from the strongest teacher is not necessarily the best supervision for a given student. To address this gap, we propose Student-Centric Answer Sampling (SCAS), a framework that selects from verified teacher-generated answers according to their estimated student-centric learning cost. Motivated by a token-wise gradient decomposition, we derive an efficient forward-only proxy for this cost and use it to guide answer selection during training. Experiments across 30 teacher models, 6 student base models, and 8 tasks show that SCAS consistently improves student performance, suggesting that effective distillation should prioritize supervision matched to the current student rather than teacher strength alone.
Anthology ID:
2026.emnlp-main.1369
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
31221–31256
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1369/
DOI:
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Cite (ACL):
Zhengyu Hu, Zheyuan Xiao, Linxin Song, Fengqing Jiang, Yuetai Li, Zhihan Xiong, Junhao Lin, Yue Liu, Yao Su, Lijie Hu, Kaize Ding, Teng Xiao, and Radha Poovendran. 2026. When the Strongest Teacher Is Not the Best Teacher: Student-Centric Answer Selection. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 31221–31256, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
When the Strongest Teacher Is Not the Best Teacher: Student-Centric Answer Selection (Hu et al., EMNLP 2026)
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https://aclanthology.org/2026.emnlp-main.1369.pdf