题目中出现的这个问题并不是我凭空想出来的,而是我的一个学生在课堂上的“一鸣惊人”之作。我很欣慰在我讲到“圆”这个章节时,有个学生从座位上一跃而起冒出了这么一句,这说明他已经开始思考这个问题了。从现象上来看,圆是自然中存在的现象,比如地球就是圆的,有些水果长出来也是圆溜溜的,人的眼球、树木的横截面等也是圆的。从应用上来说,圆是后天应用的产物,比如水桶的底、各种车的 The problem that appeared in the title was not what I imagined, but one of my students in the classroom “blockbuster” for the work. I am very pleased that when I talked about the “round” chapter, a student jumped out of his seat so that he had started to think about it. Phenomenon from the point of view, the circle is a phenomenon existing in nature, such as the Earth is round, and some fruit is also out of a round yo-yo, human eye, the cross-section of trees are also round. From the application point of view, the circle is the product of acquired applications, such as the end of the bucket, a variety of cars