在初中九年级上学期阶段始介绍平行线截比例线段性质,进而将应用于相似三角形的单元中。笔者曾做过私下访查,发现教师在教导学生此单元时大多只进行板书的讲解及学生练习等,几乎没有用于实际的测量活动。虽然各版本教科书中,都有相似三角型的应用题目,但是学生只能从“平面性”的文字及图形作“想象性”的思考。 In the ninth grade junior high school semester beginning to introduce the proportion of parallel lines truncated line segment properties, which will be applied to similar units of the triangle. I have done private interviews and found that most teachers only instruct their students to explain this booklet and practice students’ books when teaching this unit, which is rarely used for actual measurement activities. Although there are similar triangular application topics in all versions of textbooks, students can only think “imaginatively” from the “flatness” text and graphics.