Opportunistic Group Formation

1. INTRODUCTION The fact that reflection and externalization of one's understanding are effective ways of learning has been widely accepted in the field of education. Thus, much effort has been devoted to the various research subjects related to the reflection and externalization [1]. Kashihara and his colleagues, for example, have developed an intelligent self-explanation support system, called SEA, and proved it had the desired effect. SEA guides learners toward better understanding by letting them to externalize their understanding as diagrammatic representation using well-designed graphical interface and by giving reasonable guidance on self-explanation process [2]. The theory on the motivation of learning also has close relation to reflection and externalization. Hirashima and his colleagues have developed a visual physics simulator with a function to lay emphasis on the flaw of learner's understanding and shown that the method szuccessfully gets learners to motivated to make reflection and externalization on their own understanding [3]. On the other hand, the pioneer study of CSCL (Computer Supported Collaborative learning) [4] also showed that interaction with computer learning companions can promote leaners' motivation in externa-lization /self-reflection process. Since then study on CSCL based on the educational principles closely related to the reflection and externalization, such as, "Learning by teaching" and "Learning by observing" has been attracting the interest of many researchers in these years. Needless to say, such principles have no special originality from viewpoint of practice of education. Group learning in a classroom, for example, is one of popular ways of education. The innovation originated in CSCL could be found mainly in rich communication aids with high-performance network technology and multimedia technology, or understanding support of collaborative learning based