信息窗三（分数加减混合运算）

1、,R五年级下册,3. 分数加减混合运算 第1课时 分数加减混合运算,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,情景导入,同学们，今天我们来了解一下国家级景区云梦森林公园的地貌。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,探究新知,云梦森林公园地貌情况对

2、比,1 2,3 10,1 5,你能提出哪些数学问题？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,云梦森林公园地貌情况对比,1 2,3 10,1 5,森林部分,（1）森林部分比草地部分多几分之几？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,你会算吗？,这

3、是异分母分数的加减混合运算，得先通分。怎样通分好呢？,（1）森林部分比草地部分多几分之几？,这是分数加减混合运算，应该和整数加减混合运算一样，从左往右算就可以了。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,4,5,3,5,小林的方法：,小萍的方法：,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才

4、路,状元成才路,状元成才路,状元成才路,小林的方法是先把前两个数通分，计算出结果后再和第三个数通分，也就是分步通分计算的。,4,5,小林的方法：,分步通分：,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,3,5,小萍的方法：,一次通分：,小萍的方法是一次性把三个数都通分， 然后再按照从左往右的顺序计算，比小林的方法相对要简便一些。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,

5、状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,分数加减混合运算的运算顺序与整数加减混合运算的计算顺序相同。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,5,8,=,2 3,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状

6、元成才路,状元成才路,状元成才路,（2）森林和裸露地面降水转化情况对比,1 4,7 20,2 5,11 20,2 5,（ ） （ ）,裸露地面储存的地下水占降水量的几分之几？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,两种方法有什么不同？,方法1,方法2,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状

7、元成才路,状元成才路,状元成才路,状元成才路,我们的方法有什么不同呢？,我用小括号了。,我是先求储存为地下水和其他一共占几分之几，再求储存为地下水占几分之几。,先求地表水和其他一共占几分之几，再求储存为地下水占几分之几。,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,你能说一说分数加减混合运算的运算顺序吗？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,

8、状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,= 0,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,巩固提升,1. 计算。,9,5,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,11,5,状元成才路,状元成才路

9、,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,2.计算,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,课后作业,1. 课本P100，第2、3、4题； 2. 完成练习册本课时的习题。,声 明 本文件仅用于个人学