Being a complex social process, open and distance learning includes many different dynamics and interaction elements. Activity theory provides a comprehensive framework for understanding complex human interactions and the lack of appropriate methods to address the complexity of online learning environments. The main purpose of this study is to define the seven elements of interaction (subject, object, tools, rules, community, division of labor and outcome) in an online course within the framework of activity theory. In order to reach this purpose, a qualitative study has been carried out by using exploratory case study model. As a result of this study, the general activity system of the online course was identified. According to the activity system, the subject refers to the learners who attend the online course, the tools are all learning materials, learning environments and instructors in the online course, the rules incorporate all lawfully restricting codes, regulations and guidelines in the course along with the community norms, network standards and the rules determined by the learners during the synchronous courses. The community in the course is made up of all the learners who attend the online course, the instructor, forum moderators, technical staff and OEF (Open Education Faculty) management. The division of labor has been observed to be scattered among the students, the instructor, the administration and the support staff. Ultimately, the object is to pass the course and the outcomes are the ones that the course offers in its educational plan. [This paper was published in: Proceedings of "International Open & Distance Learning Conference (IODL19)" (pp. 275-282). Eskisehir, Turkey: Anadolu University.]