ETRI in South Korea has developed a Korean AI teacher that teaches Korean to foreign learners by combining free conversation with structured progress tracking.

ETRI also announces a Korean-language teaching AI capable of engaging learners in free-flow conversations while ensuring all lesson content is covered.

The system uses three mechanisms: a stage-detection component to decide when to advance, a division of labor where familiar expressions are handled by a smaller model (3 to 13 billion parameters) and unfamiliar terms are passed to general-purpose AIs like GPT, and a filter to prevent repeating questions.

In evaluations, the AI achieved the lowest conversational error rate (18.6%) compared with GPT-4o-mini (25.4%) and GPT-5.1 (23.7%), while learners preferred ETRI’s system in eight of ten scenarios, though GPT models performed better at avoiding repetition and varying expressions.

Current capabilities include situational speaking exercises, free conversation, reading-comprehension-based dialogue, and automated writing assessment, with the pilot expanding toward a comprehensive reading, writing, and speaking tutor.

Future plans include refining performance through user data collection, optimizing model role allocation, expanding to reading and writing, and offering a personalized AI Korean teacher tailored to individual proficiency and study history.

The glasses system connects ETRI’s small language model with GPT technology, alternating responses between the two models.

Lim Su-jong, head of ETRI's Language Intelligence Research Laboratory, said the results show competitiveness through external blind evaluation and highlighted ongoing development toward trusted AI education technology for Korean learners worldwide.

ETRI aims to evolve the technology into a personalized education service tailored to each learner’s proficiency and study history for global use by Korean learners.

Leaders emphasize solving fluency gaps by providing an AI native-speaker-like partner and expanding the technology into a global AI education tool for Korean learners.

The system blends ETRI’s in-house small language models (3B–13B) with general-purpose AI like GPT, routing unfamiliar terms to external models while handling familiar expressions in-house to improve consistency and reduce data sent overseas.

A novel topic-guided free-conversation approach keeps learners on learning objectives while allowing natural dialogue, with the AI controlling lesson steps without making them explicit to the learner.