一、背景描述映射是近、现代数学中的一个非常重要的概念,其思想也渗透于整个中学数学教材之中。我们知道,在原来的教材安排中,映射是安排在函数概念的教学之前,用映射的观点给函数定义,这样安排突出了映射的工具性,但是不利于学生真正理解映射的概念。而目前教材的安排是先用集合的观点给函数定义,并在研究了函数的概念和性质之后再学习研究映射。这样的安排,并不只是为了加深对函数概念的理解,知道函数是一类特 First, the background description Mapping is a modern and modern mathematics in a very important concept, its ideas also infiltrate the entire middle school mathematics textbooks. We know that in the original textbook arrangement, the mapping is arranged before the teaching of the function concept, and the definition of the function is given from the perspective of the mapping. This arrangement highlights the instrumentality of the mapping, but does not help students to understand the concept of mapping. At present, the arrangement of textbooks is to first define the function from the point of view of the collection and study the mapping of the study after studying the concept and nature of the function. This arrangement, not just to deepen the understanding of the concept of function, to know that the function is a special type