"Understanding Triangle" in the fourth grade of mathematics, a compulsory education textbook published by People's Education Press, is the first lesson of "Triangle" unit. Students have a preliminary understanding of triangles and their heights. In this lesson, we should know the characteristics and composition of triangles and master the method of drawing the height of triangles. In the process of operating, imagining and solving problems in connection with the situation, students should be guided to deepen their understanding of the surrounding things from the form and develop the concept of space.

A mathematical model is a mathematical structure that summarizes or approximately describes the characteristics, quantitative relations and spatial forms of things in the real world with mathematical language. Generalized mathematical concepts, theorems, laws, rules, formulas, properties, quantitative relations, charts and programs are all mathematical models. Mathematics textbooks in primary schools are full of mathematical models. The process of primary school students learning mathematics knowledge is actually the process of understanding and mastering a series of mathematical models.