The Graduate Certificate in STEM Education course offered to teachers in Papua New Guinea was unique, likely being the first of its kind for teachers in the country. Therefore, understanding the course's impact on the participating teachers was important. This chapter reports on research that specifically focused on the following research question: How did the course design influence teachers’ knowledge of integrated STEM education? A mixed-methods approach was adopted, with data collected through a survey and interviews. The research demonstrated that teachers’ motivation, continuous concrete experiences and opportunities for reflection, and the conceptualisation of ideas into action plans were the key factors contributing to success.