SKA (Shared-Knowledge Awareness) refers to the perception about the shared knowledge students have while working in a collaborative learning context. If we understand the shared comprehension of the problem to be solved as a key part of any collaborative learning activity, SKA will be an indispensable aspect to take into account when designing CSCL systems. In this paper, we propose some design guidelines that can help in the process of graphical user interface design for CSCL tools. We have evaluated some CSCL tools according to the proposed design guidelines depicting how these recommendations materialize in the graphical user interface of some CSCL tools.