Nowadays is well known that the learning of STEM (science, technology, engineering, and mathematics) can benefit from using Robotics technologies. Furthermore, robot-based educational activities can enhance not only the acquirement of concepts in other fields (e.g. literature, history) but even improve children emotional and social development. This paper describes how robotics has been introduced transversally at all k12 level in the school Montserrat in Barcelona, Spain. The infrastructure to support the program, the planning of the activities and research studies, a classification of these activities based on the children-robot interaction modality, and the details of some examples are described and discussed.