五上第三单元例9.用计算器探索规律市名师优质课比赛一等奖市公开课获奖课件.pptx

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,*,小数除法,用计算器探索规律,网,网,教师：谭雪光,第1页,0.3636,4,11,0.4545,5,11,一、复习旧知,用计算器计算下面各题。,1,11,0.0909,2,11,0.1818,3,11,0.2727,网,网,网,第2页,二、探索新知,111,0.0909,2,11,0.1818,3,11,0.2727,4,11,0.3636,5,11,0.4545,你发觉了什么规律？,它们商都是循环小数。,网,网,第3页,311,，商是循环小数，循步骤是,27,，,27,是被除数,3,9,倍。,411,，商是循环小数，循步骤是,36,，,36,是被除数,4,9,倍。,511,，商是循环小数，循步骤是,45,，,45,是被除数,5,9,倍。,111，商是循环小数，循步骤是09，9是被除数19倍,。,211,，商是循环小数，循步骤是,18,，,18,是被除数,2,9,倍。,1,11,0.0909,2,11,0.1818,3,11,0.2727,4,11,0.3636,5,11,0.4545,循步骤是,09,循步骤是,18,循步骤是,27,循步骤是,36,循步骤是,45,二、探索新知,你还发觉了什么规律？,第4页,不计算，用发觉规律直接写出下面几题商。,6,11,0.5454,7,11,0.6363,8,11,0.7272,9,11,0.8181,想一想,8 11,商是多少？,你是怎么想出,9 11,0.8181,这个答案？,二、探索新知,第5页,三、知识应用,6,0.7,6.6,6.7,6.66,66.7,6.666,666.7,1.,不计算，利用规律直接填出得数，再用计算器验算。,4.2,44.22,444.222,4444.2222,猜猜,6.66 66.7,积是多少？你是怎么想？,想一想,6.666 666.7,整数部分有几个,4,，小数部分又是多少？,第6页,三、知识应用,3,7,3.3,6.7,3.33,66.7,3.333,666.7,3.3333,6666.7,3.33333,66666.7,21,22.11,222.111,2222.1111,22222.11111,222222.111111,3.333333666666.7,2222222.1111111,你能用发觉规律接着写出下面一个算式吗？,2.,用计算器计算前,4,题，试着写出后,2,题积。,第7页,1,7,2,7,3,7,4,7,5,7,6,7,0.142857142857,0.571428571428,0.714285714285,0.857142857142,三、知识应用,0.285714285714,0.428571428571,你发觉了什么？,仔细观察，想一想，前,4,个算式商相同之处是什么？不一样之处又是什么？,你能用发觉规律把后面两道算式商写出来吗？,都是循环小数。,循步骤数字都是,1,、,4,、,2,、,8,、,5,、,7,。,组成循步骤,6,个数字排列次序不一样。,3.,用计算器计算下面各题。,第8页,四、布置作业,作业：第,37,页练习八，第,12,题。,第9页,