This article reports on the authors’ experience in training secondary computer science teachers in French speaking Switzerland. We present issues commonly raised during our courses and originating either from curricular or teaching decisions and describe how we tackle them using several concepts drawn from didactics. After a brief description of the cultural context, we treat questions related to: the introduction of this new discipline in secondary education; the diversity of answers regarding what computer science is and what ought to be taught; the construction of an annual plan and design of educational resources; the spatial arrangement in the classroom and its effects on teaching practices; and finally, the several means of evaluating students’ works in computer science.