With StoryCubes, a game constituted by nine dice, illustrated with various pictures, children can playfully create stories together. Through this play, they do what they have to do at school when they have to produce different written work. In the first part of this paper, conforming to French ergonomics methods, we analyse children’s activity using the instrumental approach (Rabardel, 1995). This helps understand the means of an activity from a subject’s point of view, in this case the child’s viewpoint. We focus on what children do and observe variations in their activities between, on one hand, the creation of narrative with StoryCubes game, and on the other, the collective writing of a story from an elementary school classroom. To do that, we capture the entire pedagogical sequence of the collaborative tale by being in the classroom each day, and in addition, fifteen play sessions of StoryCubes, which take place during break time. The second part of this paper demonstrates a co-design process of hybrid tools supporting narratives. It follows a conception in use, and not only for use, because we feed by the children’s activity and by what is important to them. Furthermore, this tool has the particularity to be hybrid on two levels: first it includes digital and tangible elements, to allow manipulation and exploration, and then it is positioned between game and pedagogical mechanisms to involve and motivate children, as much as possible.