The rapid development of computer-supported collaborative environments has highlighted the need for collaborative knowledge construction devices. Because most available mindtools do not promote collaboration, there is a need for social mindtools that can be used in collaborative learning situations. We have used activity theory as a conceptual framework to define the requirements of social mindtools as awareness of other participants, communication and the ability to edit common objects together. We present the concept of Woven Stories and use it as an example of an effective social mindtool. We also describe a case study in which Woven Stories software was used as an online debating forum. This case study reveals the potential inherent in the concept, compared with other text-oriented Web 2.0 tools, such as wikis.