A blended learning course for playfully teaching programming concepts to school teachers Fotis Lazarinis 1 & Christoforos V. Karachristos 1 & Elias C. Stavropoulos 1 & Vassilios S. Verykios 1 Received: 19 June 2018 /Accepted: 28 September 2018/ # Springer Science+Business Media, LLC, part of Springer Nature 2018 Abstract In this paper we report our experiences from a University outreach program with primary and secondary education teachers of various specialties. Our goal was to improve the coding abilities of teachers through Scratch activities. The participants can in turn teach their students, multiplying that way the benefitted population. To increase the participation and the completion percentage, the activities are designed as a course in Moodle realized in discrete runs with manageable groups, in a blended learning approach. The educational material was a combination of learning objects with specific objectives, video material and try-out activities. The course has been completed by 559 teachers from various Greek districts, mainly of regional areas, with a high completion rate of 65%. The participants found the experience highly satisfying, interesting and agreed that they had been supported effectively throughout the process. In the paper we describe the rational of our approach, the design and implementation phases of the project, the outcomes and the main findings of the evaluation of the user opinions. Keywords Computer science education . Computational thinking . Multimedia learning . Professional teacher development . Scratch . Blended learning . MOOC Education and Information Technologies https://doi.org/10.1007/s10639-018-9823-2 * Fotis Lazarinis fotis.lazarinis@ac.eap.gr Christoforos V. Karachristos karachrist@eap.gr Elias C. Stavropoulos estavrop@eap.gr Vassilios S. Verykios verykios@eap.gr 1 Hellenic Open University, Patras, Greece