The current study aimed to know the effectiveness of using the flipped classroom strategy in developing the environmental concepts of second-grade secondary students in the subject of geography. The research followed the quasi-experimental design. The research sample consisted of (70) students in the second grade of secondary school in the Qena Educational Administration. They were divided into two groups, one of which was experimental of (35) students who were taught the second unit of the geography curriculum (environment, its system and management) according to the flipped class strategy, and the other was a control consisting of (35) students who were taught for the same unit in the usual way for the 2019/2020 academic year. A list of environmental concepts was prepared, which was extracted after analyzing the content of the curriculum, as well as from multiple readings in this area, and an environmental concepts test, a teacher's guide, a student handbook, an educational channel on YouTube and a platform on the Edmodo website for the topics of that unit were prepared according to the inverted classroom strategy. The results of the research revealed the existence of statistically significant differences at the level of (0.05) between the mean scores of students for the control and experimental groups in testing environmental concepts for the benefit of the experimental group. Geography. It recommended the possibility of using the flipped classroom strategy in teaching different courses and for different educational stages.