Roles as a structuring tool in online discussion groups: The differential impact of different roles on social knowledge construction

This study focuses on stimulating social knowledge construction in e-discussions and examines the introduction of five roles: starter, summariser, moderator, theoretician, and source searcher. Asynchronous discussion groups of 10 1st-year students Instructional Sciences were organised to foster students' processing of the learning content. Four successive authentic tasks of three weeks each were presented. Taking into account the moment of introduction of the role assignment (at the start of the discussions versus at the end), the differential impact of the roles on knowledge construction is studied through quantitative content analysis based on the interaction analysis model of Gunawardena, Lowe, and Anderson (1997). The results show a positive effect of role assignment on students' social knowledge construction at the start of the discussions. This implies that roles should be introduced at the start of the discussions and can be faded out towards the end. With respect to the differential impact of the roles, the results show that messages from moderators, theoreticians, and summarisers reflect higher levels of knowledge construction at the start of the discussions. Even students without a role in role-supported groups benefit from the role introduction. (C) 2009 Elsevier Ltd. All rights reserved.