The first volume of the eighth grade math open class is better than the triangle line open class. According to relevant information, the triangle line segment course in the first volume of Grade 8 can show pictures of pyramids, fighter planes and bridges. Let students feel the triangle in life and realize the fun of mathematics everywhere in life. Teachers use multimedia to demonstrate the formation process of triangles. Let the students observe. It can stimulate students' interest in learning. It can also enhance the interaction between teachers and students.