The purpose of this study was to explore group forming strategies by examining participation behaviours during whole class discussions associated with active participation in a following small group activity. Written communication data, posted in class discussion forums (843 messages/70,432 words) and small group forums (732 messages/59,394 words), were analyzed quantitatively. The result indicated that individuals' participation quantity in small groups was significantly correlated with their own participation behaviour in whole class discussions. Also, a significant portion of small group participation was explained by their group members' participation (i.e., group member effect). Based on the results, we suggest instructors use the information of participation behaviours during the initial period of whole class activities for allocating students into small groups heterogeneously. (Contains 4 tables and 3 figures.)