Unlocking the Unsolvable: Teacher-Guided Curriculum for Data-Efficient RLVR

Yukang Zhu, Zhen Han


Abstract
Reinforcement Learning with Verifiable Rewards (RLVR) has shown remarkable success in improving the mathematical reasoning of large language models. Yet problems beyond the model’s current capability, where rollouts uniformly fail and no learning signal is produced, are structurally wasted despite marking the most informative training frontier. We show that these otherwise-inert problems can be unlocked via teacher-guided curriculum learning: partial reasoning traces from a stronger model create a graded difficulty landscape, and a backward-chaining curriculum progressively withdraws guidance until the model solves problems unaided. Training on only 128 unsolvable problems matches or exceeds GRPO trained on a full 2,000-problem corpus (~16× data efficiency) on the nine-benchmark average for both base models, while substantially expanding the reasoning boundary measured by pass@k at large k. Furthermore, we identify a distribution-shift cost that is particularly acute in the unsolvable-only regime and propose Monotone Frontier Curriculum (MFC), a method that monotonically drives training toward unguided solving, consistently outperforming existing curriculum methods.
Anthology ID:
2026.findings-emnlp.931
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
19639–19658
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.931/
DOI:
10.18653/2026.findings-emnlp.931
Bibkey:
Cite (ACL):
Yukang Zhu and Zhen Han. 2026. Unlocking the Unsolvable: Teacher-Guided Curriculum for Data-Efficient RLVR. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 19639–19658, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Unlocking the Unsolvable: Teacher-Guided Curriculum for Data-Efficient RLVR (Zhu & Han, Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.931.pdf