Teaching educational robotics is of growing interest in K-12 settings. Yet, immense efforts are needed to move the field forward by framing the teaching of robotics with pedagogically sound theories as well as appropriate instructional design models and strategies. To meet this need, the authors designed and implemented an online educational robotics course for inservice teachers who had little or no prior experience in teaching robotics, by applying instructional design factors as well as teaching and facilitation strategies derived from the learning by design (LBD) framework. Action research employing mixed methods was carried out to examine the effects of instructional design factors implemented in the online educational robotics course. An online survey indicated that the participating teachers increased their self-efficacy in robotics, use of problem-solving and collaboration strategies, and confidence in robotics knowledge and teaching. In addition, by the end of the course, the participating teachers demonstrated sufficient robotics content knowledge. As revealed in their reflective essays, they also developed learning strategies, such as casebased reasoning, sketches, trial and error, and evaluating capacity while completing the robotics open-ended project. Further, they realized the constraints of learning educational robotics online and the benefits of collaboration. This study sheds light on the design components of a robotics course grounded in LBD that are effective for preparing teachers in an online environment to implement robotics in their classrooms.