Educational Robotics is rapidly gaining attention as an effective methodology to develop skills and engage students preserving their peculiar style of learning. It is often tied together with two other methodologies, Coding and Tinkering, characterized by a similar hands-on approach. In order to fully exploit their inclusive features, teachers need to be prepared to introduce them into classroom. It is often noticed that in-service teachers are not yet fully prepared to face this challenge. Many actions have been established to recover this situation, but a proper method for assessing whether these actions are successful or not is not yet developed. This paper presents a methodology for introducing in-service teachers to Educational Robotics, Coding and Tinkering and for assessing the outcomes. 184 in-service teachers were assessed and results analysed. Final considerations draw a picture of the situation amongst the sample chosen for the present study, observing that the intervention seemed to be successful in providing key notions and examples, and improving teachers' self-confidence.