Massive Open Online Courses (MOOCs) are platforms teachers can use to seek guidance on different strategies to update their teaching skills. This study finds the effectiveness of MOOCs in developing professional performance and skills of school teachers. It tries to show the extent to which school teachers can benefit from these courses and how they apply them in their practical teaching. A mixed-method sequential explanatory (following up the quantitative findings with qualitative ones) method by using multiple data sources, including the MOOC system's log files, final grades and the discussion forum, with additional of face to face class snapshots was used. Some of the data were analysed using statistical, correlations and clustering models, with others coded in excel to develop different themes based on reported experiences. Results indicated how TPD core features uncover school teachers' knowledge and skills level through their learning behaviour variables for the MOOC platform, which will help to transform their pedagogical and instructional approaches while shifting their classrooms into 21st Century classrooms. Generally, this study contributes fresh insights into the literature on the importance of MOOCs for teachers' professional growth while sustaining their work and connections for networked learning. Implications for future studies are also discussed.