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1、两、三位数除以一位数的估算（教学设计）【教学内容】青岛版教材三年级数学上册第47页信息窗 1 及第 48 页内容。【教学目标】1结合具体情境让学生探究两、三位数除以一位数的估算方法，并能说出估算的过程。2在探索两、三位数除以一位数的估算方法的过程中，培养学生的知识迁移能力和概括能力。3初步体会估算的意义，感受数学与生活的密切联系，增加学习数学的兴趣。【教学重点】两、三位数除以一位数的估算【教学难点】解释两、三位数除以一位数的估算过程【教具准备】PPT【教学过程】一、创设情境，导入新课在轻音乐的伴奏下出示几张风筝的图片。师:今天我们再去风筝加工厂参观，了解鹤风筝、孔雀风筝的制作吧。在参观的过程中
2、请同学们认真观察，积极思考，你们会有很多的数学知识的收获-两三位数除以一位数的估算。（创设情境，可以有效的激发学生的学习欲望，比直接导入课题更有趣味性和探究性。）二、出示学习目标1、学会两、三位数除以一位数的估算方法，并能说出估算的过程。2、能够在探究的过程中积极思考，并与同学合作交流。3、学会运用估算解决简单的问题。三、学习新知（一）师生合作探究两位数除以一位数的估算1、出示信息窗一2、学生分析信息从图中概括出题目已知条件和所求问题。平均每天大约做多少只鹤风筝才能按时交货？学生独立找信息后，全班交流。已知条件：未交货89 只，离交货天数还有三天。所求问题：大约每天要做多少只鹤风筝？师:如何列
3、式解决问题？生：893 3、探索估算方法。提问：师：需要计算出准确的得数吗？为什么？生：不需要，因为问题中是“大约”要做多少。师：因此我们只估计是多少就可以了，也就是进行估算。学生小组讨论：学生 4 人一组，进行讨论，组长负责记录。教师：怎样进行估算？把你的想法在小组里说一说。交流汇报小组长汇报各组的讨论结果。学生共同总结出估算的方法。估算的方法：把89 只看成是 90 只。因为 89 接近于 90,90 除以3 等于 30，所以 89 除以 3 约等于 30。【“的使用】教师提醒学生注意“”的使用。因为计算的结果是一个大约的数量，不是准确的数量，所以不能用“=”，只能用约等于“”，读作“约等
4、于”4、深入思考师：平均每天做30 只鹤风筝能完成按时交货吗?请你和同桌交平均每天大约做多少只鹤风筝才能按时交货？文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH1
5、0W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X
6、4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编
7、码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P
8、8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1
9、E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7
10、G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2流一下。学生 1：把 89 看作 90 看大了，因此估
11、算的结果要比实际结果大，所以平均每天做30 只鹤风筝能完成按时交货。学生 2：平均每天做30 只鹤风筝，3 天能做 90 只，90 大于89，所以平均每天做30 只鹤风筝能完成按时交货。5、小结两位数除以一位数的估算方法小试身手：61 2 385236487鼓励学生用语言表述自己的想法，教师补充完整。两位数除以一位数的估算方法:把算式中的两位数看作最接近原数又能用表内除法的知识来解决的数，再去除以一位数，得出的商就是估算的结果。师板书课题：两位数除以一位数的估算(二)学生自主探究三位数除以一位数的估算1、解决问题平均每天大约要做多少只孔雀风筝才能按时交货？2、学生自主列式解答142720（只）
12、想：142 看作 140，1407 等于 20，所以 1427 约等于 20。答：每天大约要做20 只孔雀风筝才能按时交货。3、思考师：平均每天做20只孔雀风筝能完成按时交货吗?学生交流学生 1：把 142 看作 140 看小了，因此估算的结果要比实际结果小，所以平均每天做20 只孔雀风筝不能完成按时交货。学生 2：平均每天做20 只孔雀风筝，7 天能做 140 只，140 小于 142，所以平均每天做20 只孔雀风筝不能完成按时交货。4、探究三位数除以一位数的估算方法。再试身手：1985101232344237学生分组以竞赛形式完成。（以竞赛的形式完成，可以更好的激发学生的挑战性。）学生自己
13、总结估算的方法，教师补充完整把算式中的三位数看作最接近原数的整百数或几百几十且能用表内除法整除的数，再去除以一位数，得出的商就是估算的结果。(这样的表述更清晰，利于学生理解和掌握。)四、巩固练习，强化应用。1、数学医院下面是两位粗心的小朋友做错了，请同学们改正过来。文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W
14、2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:
15、CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V
16、10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2
17、 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2
18、D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2
19、 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W
20、4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W27924 3626=60 学生独立完成，集体交流。2、估一估，连一连992 商大约是 20 1634 商大约是 50 1377 商大约是 10 515 商大约是 40 2679 商大约是 30 学生抢答完成。3、解决问题(1)844=41 这道题计算的对吗？我能用估算解决。学生独立完成。（2）小明：我 3 分钟打字 122个。小亮:我 2 分钟打字 98 个。他们平均每分钟大约打字多少个?谁打得快？学生先独立完成再进行小组讨论，教师点拨书写的格式要完整。五、课堂总结。这节课，你都学会了什么？觉得自
21、己表现的怎么样？谈谈你的感受。文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH1
22、0W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X
23、4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编
24、码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P
25、8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1
26、E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2文档编码:CV3P8V10Z1E2 HA7G2D9I2F2 ZH10W4G1X4W2