This research investigates the role of representational guidance by comparing the effects of two different representational tools. We used a design with two different groups defined by the type of argumentative diagram students co-constructed while working in a computer-supported collaborative learning (CSCL) environment. The Graphical Debate-tool offered different representational guidance than the Textual Debate-tool. The results show that groups that worked with the Graphical Debate-tool constructed representations of higher quality and wrote essays that were better in terms of grounds quality. Furthermore, working with the Graphical Debate-tool was found to have a positive effect on students' learning as measured by a knowledge post-test. In contrast to our expectations however, there was little difference between the two conditions regarding the online collaboration process. It can be concluded that representational guidance has an impact on group and individual performance and should therefore be taken into account during instructional design.