The context of this paper is the post-graduate Certificate course for interpreter trainers, offered by the School of Translation and Interpretation at the University of Geneva. Great care must be taken in designing learning activities in the field of teacher training because the medium is also the message. To help us design socio-constructivist learning activities in a blended student centered learning environment, we used the Tutoring Support Structure engineering tool, paying particular attention to its cognitive level. We built on the principles of Cognitive apprenticeship and activity scaffolding and modelling, all of which are presented by means of a detailed example. Learners evaluated different aspects (professional relevance, reflective thinking, interactivity, cognitive demand and interpretation of meaning - the extent to which students and tutor coconstruct meaning in a congruent and connected manner-) and results are rather encouraging ((M 4.49/6, SD .5), (M 4.25/5, SD .6), (M 4.06/5, SD .7), (M 4.01/5, SD .6), (M. 3.44, SD .6)). In addition, qualitative semi-guided interviews were conducted with teaching staff; results are equally encouraging as staff considered the group of learners in question “more creative, more independent in terms of what they are able to produce”.