比例是小学数学“数与代数”的最后一块内容,其中用比例知识解决问题是本单元的重点也是难点。常规的解题思路是要求学生先找一定量,然后利用数量关系式判断成什么比例,再决定用什么方法解决问题。过去老教材很注重让学生记忆数量关系,同时也注重数量关系中各部分之间的关系,如:单价×数量=总价,总价÷数量=单价,总价÷单价=数量等。新教材淡化了这种机械的记忆与背诵,数量关系对于学生不是很熟悉,特别是不常用的数量关系对学困生而言记忆几乎为零。但是,正比例、反比例的意义则是学生比较好理解的,特别是学困生也能够理解。成正比例的量是一种量增多,另一种量也增多;一种量减少,另一种也减少;(即变化方向相同)相对应的比值一定。成反比例的量是一种量增多,另一种量反而 The ratio is the last piece of the elementary mathematics “Number and Algebra ”, and solving the problem with proportional knowledge is the key point of the unit. Conventional problem-solving ideas is to ask students to find a certain amount, and then use the number of relations to determine what proportion, and then decide what method to solve the problem. In the past, the old textbooks paid great attention to students to remember the relationship between quantity and quantity. At the same time, they also emphasized the relationship between the various parts of the quantity relationship, such as: unit price x quantity = total price, total price ÷ quantity = unit price, total price ÷ unit price = quantity, The new text has played down the memory and recitation of such machinery. The quantitative relationship is not very familiar to students. In particular, the less commonly used quantitative relationship has almost zero memory for poor students. However, the proportion, the inverse proportion of the meaning is better understood by students, especially students with learning difficulties can understand. The proportion is proportional to the amount of an increase in the amount of the other also increased; one kind of reduction, the other also reduced; (ie, the same direction of change) corresponding to a certain ratio. The amount of inverse proportion is an amount increased, the other amount instead