According to the theory of active education and Mathematics teaching in secondary schools, there are five steps designed for geometrical knowledge and four stages for the process of applying the examined circumstances. The research objective aims to evaluate the effectiveness and feasibility of the suggestion focused on the process of constructing and manipulating situations in teaching Geometry. The research method uses the case study in the specific teaching process, which was conducted with 24 teachers who have taught Mathematics at secondary schools over three months from August 2019 to October 2019; and 30 secondary school students between May 2020 and July 2020. Finally, the result shows that all teachers agree that the design and application process is appropriate and effective for their lesson. In terms of the student's aspect, the case study reveals that the application of various steps in the process is beneficial for improving geometric deductive and spatial estimation, as well as using theoretical knowledge in the practical situation. Based on the research, this paper will clarify some solutions related to the way to design processes and utilize them in some Geometry content in secondary schools in Vietnam.