Although research in collaborative learning has a fairly long history, dating back at least to the early work of Piaget and Vygotsky, it is only recently that workers have begun to apply some of its findings to the design of computer based learning systems. The early generation of the le systems focused on their potential for supporting individual learning: learning could be self paced; teaching could be adapted to individual learners' needs. This was certainly the promise of the later generation of intelligent tutoring systems. However, this promise has yet to be realised. Not only are there...