STEM education is essential but challenging. Educators generally believe that both practical work and flipped learning facilitate STEM education. Practical work is useful in establishing linkages among STEM-related disciplines as well as the connections between knowledge and the real-life problems while flipped learning allows teachers to spend more in-class time on individual guidance and feedbacks. This study aims at studying the mechanism of how they could benefit STEM education and their interactions when used together. In this study, a strategy called flipping-practical-discussion was employed in a STEM lesson among twenty senior high school students in grade eleven. The research follows a qualitative design and individual interviews were conducted on three students and the teacher who conducted the lecture. The result shows that the pre-class video of flipping classroom could act as a medium in providing the pre-requisite knowledge and skills which facilitate the practical work and discussions. Although there is a lack of support in the pre-class section, the questions aroused during watching the video could serve as the raw materials for subsequent class activities, therefore keeping students more focused in the in-class session and potentially boosting the effect of the practical work and discussions.