The article proposes a number of measures to develop students’ ability to think and reason mathematically through teaching the corner chapter with circles-Geometry 9, including: Practice for students to perform operations thinking analytically, synthesizing in the process of learning concepts, proving theorems or solving exercises on corners with circles
Train students in the operations of comparison, analogy, generalization, and specialisation in the process of solving exercises of the corner chapter with the circle
Guide students to analyze and argue from different angles to find many different solutions while solving the corner chapter exercises with circles.