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第7课时小数与单位换算(1)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
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www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com请你按照高矮顺序,给下面的小朋友排排队。80cm1m45cm1.32m0.95m这些数据太乱了,怎么比呢?改成相同计量单位的数。探索新知二
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www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com1m45cm>1.32m>0.95m>80cm你们现在能按照高矮顺序给他们排队了吗?1m45cm=1.45m探索新知二想一想:1m45cm是多少米?
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www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com24dm=()m1450g=()kg6km350m=()km8t40kg=()t2.41.456.358.04说一说你是怎么想的。对应练习三
www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com1.按照从小到大的顺序排列起来340cm3.5m35.001dm3401mm分析:340cm=3.40m35.001dm=3.5001m3401mm=3.401m340cm<3401mm<3.5m<35.001dm巩固练习四
www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com2.钉子的长度是()m。答案提示:钉子的长度是0.016m。解题思路:学生在生活中解决问题时经常会遇到长度的问题,并且要根据需求进行简单的单位换算。1.6cm÷100=0.016m;1.6cm=0.016m。0.016巩固练习四
www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com低级单位的单名数改写成高级单位的单名数的方法:用这个数除以两个单位间的进率,如果两个单位间的进率是10、100、1000……可以直接把小数点向左移动相应的位数。课堂小结五
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www.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.comwww.youyi100.com注意:只有当两个计量单位间的进率是10、100、1000……的时候才可以用小数点的移动来改写,否则只能除以进率来改写。例如:45分=()时,应当用45÷60来改写。课堂小结五