教师通常是以椭圆的机械画法引入《圆锥曲线 .椭圆》这一内容的 .也有教师先讲海尔 .波普彗星的现象 ,或者拿出一个圆锥模型让学生观察截面的形状 ,再由机械画法引出椭圆的定义以及焦点的概念 .这样的教学是教师直接地、生硬地把概念“抛”给了学生 .尤其是“焦点”,更象是“从 Teachers often introduce the content of “conical curve. ellipse” by means of elliptical mechanical painting. There are also teachers who first talk about the phenomenon of Hey. Pop’s comet, or come up with a conical model for students to observe the shape of the cross-section, and then mechanical painting. The law leads to the definition of the ellipse and the concept of focus. Such teaching is that the teacher “throws” the concept directly and bluntly to the student. Especially “focus” is more like “from