在和八年級学生研究“相似三角形”問題时,可以进行几个有趣和有益的实际工作。而其中特別有趣的是测量不能或难以直接测量的物体之高度。在八年級研究“相似三角形”时,我採用了一种專門的仪器,它的一般形狀和構造如圖1所示。仪器的構造非常簡單,因此在敎师的帮助下学生就能自己动手做成。它的主要部份是組成直角三角形ABF的三根木条。Г形木条BC借 There are several interesting and useful practical tasks that can be carried out in the study of “similar triangles” by students in grade eight. Of particular interest is the measurement of the height of objects that cannot be or are difficult to measure directly. In the eighth grade study of “similar triangles”, I used a specialized instrument whose general shape and configuration are shown in Figure 1. The structure of the instrument is very simple, so the student can do it by himself with the help of the teacher. Its main part is the three wooden strips that make up the ABF. Г-shaped wooden strip borrowed from BC