LLMs Are Already Good Tutors: Training-Free Prompt Optimization for Pedagogical Math Tutoring

Fuente: arXiv
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Main Authors: Lee, Unggi, Shin, Minchul, Jeong, Yeil, Lee, Sookbun, Moon, Jeongsu, Joo, Kyungtae, Lee, Eunjoo, Kwon, Hoilym
Format: Preprint
Published: 2026
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author Lee, Unggi
Shin, Minchul
Jeong, Yeil
Lee, Sookbun
Moon, Jeongsu
Joo, Kyungtae
Lee, Eunjoo
Kwon, Hoilym
author_facet Lee, Unggi
Shin, Minchul
Jeong, Yeil
Lee, Sookbun
Moon, Jeongsu
Joo, Kyungtae
Lee, Eunjoo
Kwon, Hoilym
contents Aligning LLMs for math tutoring typically requires RL-based training with multi-GPU infrastructure. We investigate whether training-free prompt optimization-evolving only the system prompt via API calls-can serve as a practical alternative. We adapt 7 published methods and propose 5 education-specialized methods, evaluating these 12 methods under 5 conditions on 2 OOD benchmark suites. All 12 best-per-method configurations surpass the strongest RL-trained baseline (R_total = 0.633), and our ParetoGrad achieves the best Pareto balance across post-test solve rate, leak control, and helpfulness, rather than dominating any single component. Behavioral analysis with an 82-code educational codebook reveals that training-free methods rely on teaching-knowledge patterns at 2-3x the rate of RL-trained models, with a compensating ~10 percentage-point reduction in intent-level scaffolding. We also find a task-dependent reasoning mode effect consistent across training-free and RL-based paradigms. Our approach enables efficient development of pedagogically aligned LLM tutors with prompts alone and minimal compute.
format Preprint
id arxiv_https___arxiv_org_abs_2605_27088
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle LLMs Are Already Good Tutors: Training-Free Prompt Optimization for Pedagogical Math Tutoring
Lee, Unggi
Shin, Minchul
Jeong, Yeil
Lee, Sookbun
Moon, Jeongsu
Joo, Kyungtae
Lee, Eunjoo
Kwon, Hoilym
Computation and Language
Machine Learning
Aligning LLMs for math tutoring typically requires RL-based training with multi-GPU infrastructure. We investigate whether training-free prompt optimization-evolving only the system prompt via API calls-can serve as a practical alternative. We adapt 7 published methods and propose 5 education-specialized methods, evaluating these 12 methods under 5 conditions on 2 OOD benchmark suites. All 12 best-per-method configurations surpass the strongest RL-trained baseline (R_total = 0.633), and our ParetoGrad achieves the best Pareto balance across post-test solve rate, leak control, and helpfulness, rather than dominating any single component. Behavioral analysis with an 82-code educational codebook reveals that training-free methods rely on teaching-knowledge patterns at 2-3x the rate of RL-trained models, with a compensating ~10 percentage-point reduction in intent-level scaffolding. We also find a task-dependent reasoning mode effect consistent across training-free and RL-based paradigms. Our approach enables efficient development of pedagogically aligned LLM tutors with prompts alone and minimal compute.
title LLMs Are Already Good Tutors: Training-Free Prompt Optimization for Pedagogical Math Tutoring
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2605.27088