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一、教学目的及教材分析.本单元的教学目的是使学生认识数量关系中的比的关系及正、反比例的关系,并能应用比和比例解决比例尺、按比例分配以及正、反比例方面的实际问题.同时渗透一些函数思想,为学生今后学习函数打下基础.教材分为两个部分.第一部分讲比,分两个层次,第一层是在除法的基础上,通过同类量的比和不同类量的比的实例引入比的概念,概括出比的意义.根据比与除法、分数的关系,类推出比的基本性质以及化简比的方法.第二层是比的概念的实际应用.包括:1.通过化简图上距离与实际距离组成的比,归纳出比例尺的意义、关系式以及用方程求实际距离和图上距离的方法.2.讲按比例分配问题
First, the purpose of teaching and textbook analysis. The purpose of this unit is to enable students to understand the relationship between the number of relations and the relationship between positive and negative, and the ratio can be used to solve the scale, the proportion of distribution and the positive and negative aspects of the actual Problem.At the same time infiltration of a number of functional thinking for students to lay the foundation for future learning function.The teaching material is divided into two parts.The first part is about ratio, divided into two levels, the first is based on the division, the same type of ratio and different According to the relationship between the ratio and the division, the basic nature of the analogy, and the method of simplifying the ratio, the second level is the practical application of the concept of ratio. Including: 1. Through the simplified map of the distance and the actual composition of the distance, summed up the significance of the scale, the relationship between the equation and the actual distance and distance on the map method.2.Proportion of the problem