What kind of knowledge activities are required in order for students to conduct online group work activities successfully in distance education? This paper reports on the knowledge activities involved within online group work in distance education. It explains the types of knowledge used in these activities. The research is a qualitative case study set within an activity theory framework. Participatory observation and documentation are the data collection techniques used. It investigated student knowledge activities in a postgraduate subject called “Information Management in Organizations”. A learning management system (LMS) called Interact (powered by Sakai) was explored. Students were grouped together to work online with team members geographically distributed over Australia and around the world. Students progressively developed their assignment in Wiki and use other group work tools for their communication and storage of documents. Data collected from participatory observation and documentation were used to investigate the group work knowledge activities. The research will report the various knowledge activity improvements explored. It proposes a model of an activity system that explains how knowledge activities are represented through activity theory notions for distance education online group assessments.