,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,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,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,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,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,*,*,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,单击此处编辑母版标题样式,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,3.,小数点移动引起小数大小的变化,第,1,课时 小数点的移动引起小数大小变化的规律（,1,）,R,四年级下册,3.小数点移动引起小数大小的变化第1课时 小数点的移动引,温故知新,1,.,口答。,（,1,）,7,扩大到原来的,2,倍、,10,倍、,100,倍各是多少？,（,2,）,5000,缩小到原来的,、,、,各是多少？,温故知新1.口答。,状元成才路,2,.,比较小数的大小。,1.25,1.250,62.8,6.28,仔细观察这几个小数，说一说你有哪些发现？,状元成才路2.比较小数的大小。仔细观察这几个小数，说一说,你们知道我是谁吗？,你们知道我是谁吗？,状元成才路,状元成才路,下面我们边听故事边收集有关的数学信息，看看孙悟空的金箍棒的长短发生了什么变化。,状元成才路状元成才路 下面我们边听故事边收集有关的数学,小数点的移动与 的长短有什么关系？,小数点的移动与 的长短有什么关系？,0.009m0.09m0.9m9m,小数点往右移，越变越大！,观察这几个小数，说一说它们有什么不同？,0.009m0.09m0.9m9m小数点往右移，,0,.,09 m,0,.,009 m,将金箍棒的长度单位转化成毫米，再进行比较。,9 mm,90 mm,0,.,9 m,900 mm,9 m,9000 mm,从上往下观察,小数点的移动与金箍棒的长短有什么关系？,0.09 m 0.009 m 将金箍棒的长度,状元成才路,我发现,0,0,0,9,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,右,乘,10,扩大,10,倍,0.009 m,10,0.09 m,9 mm,10,90 mm,状元成才路,0,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,右,乘,10,扩大,10,倍,0.009 m,10,0.09 m,9 mm,10,90 mm,0,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,右,乘,10,扩大,10,倍,0.009 m,10,0.09 m,9 mm,10,90 mm,状元成才路我发现0009.小数点向（）移动（,我发现,0,0,0,9,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,右,乘,100,扩大,100,倍,0.009 m,100,0.9 m,9 mm,100,900 mm,我发现0009.小数点向（）移动（）位右,我发现,0,0,0,9,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,右,三,乘,1000,扩大,1000,倍,0.009 m,1000,9 m,9 mm,1000,9000 mm,我发现0009.小数点向（）移动（）位右,小数点向右,移动一位，小数就扩大到原数的,10,倍；,移动两位，小数就扩大到原数的,(),倍；,移动三位，小数就扩大到原数的,(),倍；,100,1000,小数点向右1001000,0,.,09 m,0,.,009 m,9 mm,90 mm,0,.,9 m,900 mm,9 m,9000 mm,小数点的移动与金箍棒的长短有什么关系？,从下往上观察,0.09 m 0.009 m 9 mm90 mm,我发现,0,9,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,左,一,除以,10,缩小,9 m,10,0.9 m,9000 mm,10,900 mm,我发现09.小数点向（）移动（）位左一除,我发现,0,9,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,除以,100,缩小,9 m,100,0.09 m,9000 mm,100,90 mm,0,我发现09.小数点向（）移动（）位除以1,0,我发现,0,9,.,小数点向（）移动（）位,小数相当于把原数（），,小数就（）到原数的（）；,左,三,除以,1000,缩小,9 m,1000,0.009 m,9000 mm,1000,9 mm,0,0我发现09.小数点向（）移动（）位左三,小数点向左,移动一位，小数就缩小到原数的 ；,移动两位，小数就,缩小,到原数的,(),；,移动三位，小数就,缩小,到原数的,(),；,小数点向左,填一填,把,2.3,的小数点向右移动一位，原数就（）到原来的,（）,倍。,把,0.375,扩大到原来的,100,倍，小数点向（）移动,（）位。,把,0.73,的小数点向,（）移动（）位，原数缩小到原来的,。,把,30,的小数点向（）移动（）位，原数变成,0.003,。,扩大,10,右,两,左,两,左,三,填一填把 2.3 的小数点向右移动一位，原数就（,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,状元成才路,状元成才路,判 断,把,6.5,扩大到它的,10,倍是,560,。,把,1.502,的小数点去掉，它的值就缩小到原来的,1000,倍。,把,6.25,改写成,0.0625,它的值就缩小到原数的 。,甲数的小数点向右移动两位后与乙数相等，甲数是乙数的,100,倍。,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,下面各圈里的数同圈上的数比较，有什么变化？,小结：,应用小数点移动引起小数大小变化的规律，可以把一个数扩大或缩小。,下面各圈里的数同圈上的数比较，有什么变化？小结,在里填上“,”,或“,”,，在里填上适当的数。,0.37,=3.7,7.26,=7260,30,=0.3,0.87,=0.0087,10,1000,100,100,在里填上“”或“”，在里填上适当的数,状元成才路,状元成才路,状元成才路,通过本节课的学习，你有哪些认识和收获？,课堂小结,状元成才路状元成才路状元成才路通过本节课的学习，你有哪些认识,课后作业,1.,课本,P46,，第,1,题；,2.,完成练习册本课时的习题。,课后作业1.课本 P46，第 1 题；,