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A joint research team from KAIST has successfully developed and deployed a virtual teaching assistant (VTA) that provides personalized feedback to individual students even in large-scale classes. The team was led by Prof. Yoonjae Choi of the Kim Jaechul Graduate School of AI and Prof. Hwajeong Hong of the Department of Industrial Design.

"At first, I didn't have high expectations for the Virtual Teaching Assistant (VTA), but it turned out to be extremely helpful—especially when I had sudden questions late at night, I could get immediate answers," said Jiwon Yang, a Ph.D. student at KAIST. "I was also able to ask questions I would've hesitated to bring up with a human TA, which led me to ask even more and ultimately improved my understanding of the course."

This study marks one of the first large-scale, real-world deployments in Korea, where the VTA was introduced in the "Programming for Artificial Intelligence" course at the KAIST Kim Jaechul Graduate School of AI, taken by 477 master's and Ph.D. students during the Fall 2024 semester, to evaluate its effectiveness and practical applicability in an actual educational setting.

The AI teaching assistant developed in this study is a course-specialized agent, distinct from general-purpose tools like ChatGPT or conventional chatbots. The research team implemented a Retrieval-Augmented Generation (RAG) architecture, which automatically vectorizes a large volume of course materials—including lecture slides, coding assignments, and video lectures—and uses them as the basis for answering students' questions.

When a student asks a question, the system searches for the most relevant course materials in real time based on the context of the query, and then generates a response. This process is not merely a simple call to a large language model (LLM), but rather a material-grounded question-answering system tailored to the course content—ensuring both high reliability and accuracy in learning support.

Sunjun Kweon, the first author of the study and head teaching assistant for the course, explained, "Previously, TAs were overwhelmed with repetitive and basic questions—such as concepts already covered in class or simple definitions—which made it difficult to focus on more meaningful inquiries.

"After introducing the VTA, [we saw that] students began to reduce repeated questions and focus on more essential ones. As a result, the burden on TAs was significantly reduced, allowing us to concentrate on providing more advanced learning support."

In fact, compared to the previous year's course, the number of questions that required direct responses from human TAs decreased by approximately 40%.

The VTA, which was operated over a 14-week period, was actively used by more than half of the enrolled students, with a total of 3,869 Q&A interactions recorded. Notably, students without a background in AI or with limited prior knowledge tended to use the VTA more frequently, indicating that the system provided practical support as a learning aid, especially for those who needed it most.

The analysis also showed that students tended to ask the VTA more frequently about theoretical concepts than they did with human TAs. This suggests that the AI teaching assistant created an environment where students felt free to ask questions without fear of judgment or discomfort, thereby encouraging more active engagement in the learning process.

According to surveys conducted before, during, and after the course, students reported increased trust, response relevance, and comfort with the VTA over time. In particular, students who had previously hesitated to ask human TAs questions showed higher levels of satisfaction when interacting with the AI teaching assistant.

Professor Choi, the lead instructor of the course and principal investigator of the study, stated, "The significance of this research lies in demonstrating that AI technology can provide practical support to both students and instructors. We hope to see this technology expanded to a wider range of courses in the future."

The research team has released the system's , enabling other educational institutions and researchers to develop their own customized learning support systems and apply them in real-world classroom settings.