This paper describes the development of augmented group awareness tools that take mutual user ratings of their online discussion contributions as input, aggregate these data, and visually feed these data back to the members in real time, thereby informing participants about how the group as a whole perceives their contributions. A specific group awareness tool was experimentally tested in a CSCL scenario using online controversies about a physics domain. The learning material was distributed across group members to create a situation where an individual minority member with a scientifically correct viewpoint faces a majority favoring a plausible, but incorrect viewpoint. It was hypothesized that in unsupported CSCL groups an incorrect majority would dominate a correct minority, whereas in groups that were supported by an augmented group awareness tool minority influence could be strengthened by making minority contributions salient. The paper reports results in support of this hypothesis, and discusses the mechanisms leading to the benefits of group awareness tools for collaborative learning.