Digital tabletops, with their multi-touch surfaces, are innovation that could provide new opportunities for learning. They could support rich interactive collaborative activities while maintaining natural face-to-face communication. Nevertheless, we still know little about the potential learning outcomes and the situations they favor. We have explored how group activities on tabletops could encourage collaboration on the same tabletop but also between multiple tabletops. In particular, we focus on the potential of tabletops to favor learning during a brainstorming activity.