In this qualitative case study, we examined in-service elementary school teachers' learning of coding and robotics in a blended professional learning course developed and delivered through the collaboration between university faculty and a school district. We focused on activity theory to understand and reveal the mediations, conflicts, and effective practices that facilitated or hindered teachers' learning of coding and robotics. The participants of the study were twelve teachers from five different elementary schools in a rural school district. Data collection and generation sources included interviews, videos of class meetings, course assignments, and artifacts. In analyzing the data, we employed analytical approaches under the guidance of activity theory. The findings showed that teacher collaboration, coding/robotics platforms employed during the professional learning course, instructional approaches, and resources in and outside the professional learning setting mediated or conflicted with the teachers' learning of coding and robotics depending on the way that each of these elements was employed in the course. Elaborating on these elements, we reported the implications for further research and practice.