This chapter explores the flipped classroom approach, which shifts content delivery to online video lectures, freeing up class time for student-centred activities. Widely adopted in K-12 science education in Western countries, its use is expanding in Mainland China and Hong Kong. The chapter reviews the background of flipped classrooms, including their origin, definition, practice, and theoretical framework. It also examines trends in their use in K-12 science education in these regions. Several studies on flipped science classrooms in China and Hong Kong are reviewed, comparing their designs, instructional practices, impacts, and challenges. A case study in a Hong Kong secondary school demonstrates the implementation of a flipped classroom using the technology-enhanced predict-observe-explain (POE) strategy, offering practical guidance for educators. The chapter concludes with insights and implications for future research and practice in flipped science classrooms in China and Hong Kong. Copyright © 2025 selection and editorial matter, Timo Ehmke and John Chi-Kin Lee; individual chapters, the contributors.