Collaborative fantasy play and storytelling serve an important role in preschool children's development. Making up characters and telling stories are activities through which children make sense of and test out their hypotheses about the world. While computers are increasingly present to support young children's collaboration in school tasks, there is a lack of computational systems to support children's voice in this kind of important collaborative activity. StoryMat is a system that supports children's collaborative fantasy play and storytelling. With StoryMat, however, collaboration can take place among co-present peers, or between a child and a previous user, mediated by the StoryMat. StoryMat records and recalls children's own narrating voices, and the movements they make with their toys on the mat. Stories from the past are conjured up on the mat as a narrating moving shadow of the toy, when they are triggered by the present stories that are similar. By hearing peer stories in response to their own story, children's stories and the experience of telling them seem to become richer. This paper addresses the importance of supporting children's collaboration in fantasy play and storytelling and suggests a new way for technology to play an integral part in that activity.

Keywords - peer collaboration, storytelling, fantasy play