Computing education in schools faces several problems, such as a lack of computing teachers and time in an already overloaded curriculum. A solution can be a multidisciplinary approach, integrating the teaching of computing within other subjects, creating the need to motivate teachers from other disciplines to teach computing in middle school. Therefore, the motivation and training of in-service teachers becomes crucial, as they need to have computing content and technological knowledge as well as pedagogical content knowledge. Yet, so far there exist very few training programs. Thus, as part of a comprehensive outreach program, we present a study on a one-day taster workshop for middle school teachers on physical computing education. Participants learn computer programming practice and computational thinking by programming an interactive robot. The workshop also approaches pedagogical aspects for teaching computing and technical issues regarding the installation and preparation of the required hardware/software. Preliminary results of its application with public school teachers in Florianopolis/Brazil are positive, motivating the majority of participants to introduce computing into their classes. However, our results also highlight that in order to enable teacher to apply the workshops effectively, longer training courses and ongoing support is required.