资源描述
,小数点向左移动的变化规律及单位的改写,返回,冀,教版,数学,五年级,上,册,小数点,向左移动的变化规律及单位的改写,课前导,入,探究新知,课堂小结,课后作业,小数乘法,课堂练习,2,课前导,入,你知道小数点,为什么 “厉害”,吗？,九折,八五折,探究新知,把,5,米长的彩带平均分成,10,份、,100,份、,1000,份，每份,各是,多少米？,写出除法算式，结果用小数表示。,（,1,）把,5,米长的彩带平均分成,10,份，每份是,5,分米,，,5,分米可以写成,0.5,米。,除法算式：,（,2,）把,5,米长的彩带平均分成,100,份，每份是,5,厘米,，,5,厘米可以写成,0.05,米。,除法算式：,（,3,）把,5,米长的彩带平均分成,1000,份，每份是,5,毫米,，,5,毫米可以写成,0.005,米。,除法算式：,5,10,= 0. 5(,米,）,5,100,= 0.,05,(,米,）,5,1000,= 0.,005,(,米,）,510,0.5,5100,0.05,51000,0.005,观察这几个算式，你发现了什么？,5,除以,10,，,5,的小数点就向左移动一位。,5,除以,100,510,0.5,5100,0.05,51000,0.005,小数点向左移动的变化规律：,小数点向左移动,一,位，这个数缩小到原来的,；,小数点向左,移动,两,位,，这个数缩小到原来,的,；,小数点向左,移动,三,位,，这个数缩小到原来,的,；,试一试,直接写出下面各题的得数，再用计算器检验一下。,53.8,10=,53.8,100,=,53.8,1000,=,5.38,0.538,0.0538,53.81000,，小数点向左移动三位，位数不够了，怎么办？,位数不够时，要用,0,补足哟！,说一说你是怎样做的。,把梅花鹿的身高改写成以米为单位的数,。,我的身高是,85,厘米。,85,厘米,=,米,=0.85,米,把厘米改成米，要除以进率,85,100=0.85,米,把,低,级单位的数改写成高级单位的数，要除以进率。,4502,200.5,97,8.6,课堂练习,1,按要求填写下表。,450.2,45.02,4.502,2.005,20.05,0.2005,9.7,0.97,0.097,0.86,0.086,0.0086,课堂练习,1,按要求填写下表。,小汽车,白鳍豚,金丝猴,龟,速度（米,/,分）,1835,1330,630,4.2,速度（千米,/,分）,1.835,1.33,0.63,0.0042,2,算一算。,10.6,100,6,1000,5.8,100,30,100,45.6,10,42.75,10,900,1000,0.8,100,0.106,4.56,0.9,0.006,0.058,0.008,4.275,0.3,0.12,100,3.65,1000,19,100,0.91,1000,0.42,100,90.2100,12,0.0042,0.00365,0.19,9020,910,2,算一算。,3,在,里填上“,”“”,或“”。,50.610,5.06,3.8100 0.38,567801000 56.78,9.5710 95.7,0.5610 5.6,3.7810 0.0378,=,=,85,分米,(,),米,70,平方厘米,(,),平方分米,75,米,(,),千米,230,千克,(,),吨,720,毫升,( ),升,4,在括号里填上适当的数。,8.5,0.7,0.075,0.23,1,分米,=0.1,米,1,平方厘米,=0.01,平方分米,1,米,=0.001,千米,1,千克,=0.001,吨,0.72,1,毫升,=0.001,升,5,千克,400,克,(,),千克,4,米,5,厘米,(,),米,8,吨,60,千克,(,),吨,9,平方米,8,平方,分米,=( ),平方米,3,升,450,毫升,(,),升,4.05,8.06,5.4,9.08,4,在括号里填上适当的数。,3.45,5,改错。,1,克,=0.001,千克,7,千克,70,克,( 7.7),千克,改正：,7,千克,70,克,(,),千克,8,米,7,厘米,(,8.7,),米,改正：,8,米,7,厘米,(,),米,7.07,1,厘米,=0.01,米,8.07,6,在,下面的括号里填上合适的数。,载重是,4500,千克，合（ ）吨。,马拉松,全长,是,42,千米,195,米，合（ ）千米。,4.5,42.195,这节课你们都学会了哪些知识？,课堂小结,小数点向,左,移动,的,规律,小数点,向左移动一位、两位、三位,，所得的数就缩小到原来,的,、,、,如果小数位数不够时，要用,0,补足。,课堂小结,把低级,单位的数改写,成高级,单位的数,用低级,单位前面的,数除以进,率，位数不够的用“,0”,补足,。,1.,从教材课后习题中选取；,2.,从课时练中选取。,课后作业,
展开阅读全文