In recent years, hybrid education has gained attention for teaching and interacting with two groups simultaneously, where both teachers and students face challenges with interaction. We hypothesise that transactional distance plays a role in this. This study, aims to explore the characteristics of hybrid education in terms of interaction and transactional distance. In this case study, we observed four hybrid lectures of a university course on the history of physics. After each lecture, the students (N = 6) completed a transactional distance survey and students and teachers participated in individual semi-structured interviews. Our findings indicate that online students experienced limited engagement in group discussions, mainly asking for clarification when teachers asked questions. Moreover, online students experienced a greater transactional distance compared to their onsite counterparts. This disparity in engagement and perceived distance may stem from the online students' inability to partake in the informal interactions occurring before, during, and after the lectures. Both students and teachers stressed the importance of this small talk when discussing the differences between online and onsite students. In conclusion, our research underscores the essential role of informal interactions in hybrid education, highlighting the need to facilitate these exchanges to build community and enhance learning.