The work presented in this paper discusses the supported forms of the "communication-scaffolding" tools (i.e. sentence openers and communication acts) and the adaptation framework of a synchronous communication tool, called ACT. The main idea of the adaptivity lies in the provision of those "communication-scaffolding" tools that facilitate/support the group dialogue and promote student interaction/collaboration with respect to (i) the skills that the collaborative learning activities or the model of collaboration aim to develop to the students and/or (ii) the educational tool used for performing the activity. In order to determine the most appropriate set of the "communication-scaffolding" tools, a series of three qualitative empirical studies was conducted. The results of the studies drew implications about the form of the dialogue/ "communication-scaffolding" tools as well as the adaptivity of the provided "communication-scaffolding" tools.