第1课时小数的意义小数的意义和性质4优翼www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com情景导入一 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com问题：1.对于小精灵提出的问题，你有什么想法吗？1探索新知二用复名数、分数或小数来表示。 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com问题：2.生活中，你见过哪些地方用到小数？1探索新知二 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com初步探究一位小数的改写问题：1.把1米平均分成10份，你能用分数或小数表示出其中的1份吗？1dm101m0.1m探索新知二 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com初步探究一位小数的改写2.0.1表示什么意思？图中还有哪部分表示0.1？3.0.1和又有怎样的关系？101探索新知二1dm101m0.1m www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com1dm101m0.1m问题：4.第2个红色箭头所指的刻度可以表示多少分米？用分数和小数表示出它代表多少米。()dm()m()m31030.3探索新知二 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com问题：5.0.3和0.1有什么关系？探索新知二1dm101m0.1m()dm()m()m31030.3 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com问题：6.第3个红色箭头所指的刻度呢？小结：分母是10的分数可以写成一位小数。分子是几，就是几个0.1。探索新知二1dm101m0.1m()dm()m()m()dm()m()m31030.371070.7 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com小结：分母是100的分数可以写成一位小数。分子是几，就是几个0.01。探索新知二10030.0310070.07 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com理解三位小数的改写问题：1.把1米平均分成1000份，其中的1份用分数怎样表示？用小数怎样表示？探索新知二0.001m10001m www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com理解三位小数的改写问题：2.第2个和第3个红色箭头所指的刻度用分数和小数分别可以怎样表示？探索新知二()m()m()m()m0.001m10001m100060.0061000130.013 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com小结：分母是1000的分数可以写成三位小数。分子是几，就是几个0.001。探索新知二理解三位小数的改写()m()m()m()m0.001m10001m100060.0061000130.013 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com分母是10、100、1000……的分数可以用小数表示。探索新知二理解三位小数的改写()m()m()m()m0.001m10001m100060.0061000130.013 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com认识小数的计数单位和进率…亿千万百万十万万千百十一（个）十分之一百分之一千分之一….问题：1.我们在学习整数的过程中，认识了哪些计数单位？它们之间有什么关系？探索新知二 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com问题：2.1个一是10个（）；1个十分之一是10个（）；1个百分之一是10个（）；………亿千万百万十万万千百十一（个）十分之一百分之一千分之一…101100110001探索新知二认识小数的计数单位和进率. www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com小结：小数的计数单位是十分之一、百分之一、千分之一······分别写作0.1、0.01、0.001······每相邻两个计数单位之间的进率是10。探索新知二认识小数的计数单位和进率…亿千万百万十万万千百十一（个）十分之一百分之一千分之一…. www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com0.60.7107分数：小数：1060.3210032分数：小数：1.巩固练习三 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com分数：（）米（）米（）米小数：（）米（）米（）米幼儿身高8分米桌子高85厘米小蚂蚁身长4毫米0.80.850.0042.巩固练习三 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com3.在（）里填上适当的小数。1.41.2解题思路：根据小数的意义，先用自己熟悉的单位读出数据，然后换算成题目要求的单位作答。巩固练习三 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com巩固练习三 www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com在进行测量和计算时，往往不能正好得到整数的结果，还需要把一个单位分成10份、100份、1000份等较小的单位来量，从而产生了小数。（1）把单位“1”分成10份、100份、1000份……这样的一份或几份可以用分母是10、100、1000……的分数来表示，也可以用小数来表示。（2）小数的计数单位是十分之一、百分之一、千分之一……分别写作0.1、0.01、0.001……小数每相邻两个计数单位之间的进率是10。课堂小结四