The authors develop a framework for the design of tools to mediate collaboration intended to lead to learning. We identify two categories of media that are common in computer-supported collaborative learning and software in general: communication media and information media. These two types of media are then mapped onto two types of social activities in which learning is grounded: dialogue and monologue. Drawing on literature in learning theory, we suggest the need for interfaces that help students to transition from dialogue to monologue and back again. We examine in detail two cases of students participating in a computer-mediated science learning activity that involved technologies designed to support this transition, and suggest ways that the "middle space" can be supported with software and activities that transcend some of the traditional tradeoffs associated with information and communication interfaces.