“…They mainly investigate the enhancing teachers' professional development through issues of improvement, such as content knowledge, beliefs, and teaching practices of in-service and pre-service teachers, take place in different countries and use quantitative and qualitative approaches (Gordillo et al, 2019;Menon & Banerjee, 2019;Rahimi et al, 2018). Nevertheless, only a narrow range of studies have focused on the effectiveness of TPD-MOOCs (Gamage et 3 / 14 al., 2016;Reddy & Pabolu, 2019) and very limited studies investigate the MOOCs impact on teachers' selfefficacy beliefs (Aji & Khan, 2019;Gosselin et al, 2010;Mertasari & Candiasa, 2020;Wang & Zhu, 2019;Yoo, 2016). Specifically, Aji and Khan (2019) measured the self-efficacy beliefs of 16 math's and 18 science teachers in the USA, who participated in a workshop related with teaching math's and physics concepts to middle school students.…”