How can we know what has happened within a work group? How can we visualize the non-visual? How can we evaluate forms of interaction in the context of group work? These are some of the questions we tried to answer with Qlim, using online brainstorming activities. To achieve this goal, we collected data related to users' activities, then we used several visualization techniques to show the evolution of the interactions: zoomable graphs to get more detailed information and synthetic graphs to allow an overall perception of the activity using colorization and fill.