As part of the interactionist lineage of vocational didactics [1], Rabardel and Samurçay’s [2] proposal for a “system of interdependent mediations” is the inspiration for an analysis of mediations during research into the activity of designing teaching scenarios between trainers via a digital device called Ersce: Echanges de ressources scénarisées [3, 4]. This system enables scenarios to be shared on a platform for Centres de Formation Professionnelle et de Promotion Agricole, which provide training solutions for their partners. Peer-to-peer support helps trainers to get to grips with the system and develop scenarios which, once designed, are entered into a database so that they can be shared nationally. These scenarios correspond to learning strategies that have been tried and tested in practice by the trainers who write them. In the form of a process, they articulate teaching sequences combining learning activities and training resources. The results of the analysis show that digital mediations are part of human and social mediations, and that the latter play an equally important role in extending the power to act of the trainers involved. As a result, a number of design and training perspectives can be put forward.