Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,11/7/2009,#,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,*,分数的产生和意义,马郎小学 陈伟,分数的产生,（）,2、是把单位“1”平均分成（）份，表示这样（）份的数。,For Chinese a true friendship endures throughout life changes.,我国的数学古书九章算术是世界上系统地叙述分数的最早著作，它所总结的分数运算方法和现代所用的方法是基本一致的。,1 2 1 1-4 5 9 3,由许多物体组成的一个整体：如一堆沙、全班同学、12面旗帜、6个苹果,A friend in China is someone who offers help without waiting to be asked.,图中的涂色部分能不能用下面的分数表示？,This is the best of guanxi(关系),the Wide Web that connects Chinese through time and space.,通过今天的学习，我们知道了在很早以前我们人类为了解决实际生产和生活中不能用整数表示结果的问题，就已经开始用分数来表示了，经过几千年的发展，我们对于分数的应用也变得更熟练更广泛。,我国的数学古书九章算术是世界上系统地叙述分数的最早著作，它所总结的分数运算方法和现代所用的方法是基本一致的。,A friend in China is someone who offers help without waiting to be asked.,3、1 和 单位“1”相等(),把5米长的绳子平均分成2份,这里单位“1”是(),每份是5米的(),把5米长的绳子平均分成2份,这里单位“1”是(),每份是5米的(),像刚才在进行测量，分物或计算时，往往不能正好得到整数的结果，这时常用分数表示。,分数走过的历史,我国的数学古书九章算术是世界上系统地叙述分数的最早著作，它所总结的分数运算方法和现代所用的方法是基本一致的。像 这样系统地叙述，印度迟至公元7 世纪才出现，而欧洲则在 15世纪以后，才逐渐形成现代的分数的算法。足见我国古人的伟大数学智慧。,分数的意义,the difference in China and the West,（）,A friend in China is someone who offers help without waiting to be asked.,If the people do not see each other regularly,the relationship is likely to die.,（）,4、把单位“1”平均分成8份，取其中的5份，就是 八分之五 （）,A friend in China is someone who offers help without waiting to be asked.,图中的涂色部分能不能用下面的分数表示？,一个物体、一些物体等都可以看作一个整体，把这个整体平均分成若干份，这样的一份或几份都可以用分数来表示。,If the people do not see each other regularly,the relationship is likely to die.,You would not expect a friend to drop everything to respond to a non-urgent need such as shopping.,Nor would you expect a friend to recognize and respond to your wishes without stating them.,由许多物体组成的一个整体：如一堆沙、全班同学、12面旗帜、6个苹果,Westerns expect friends to be independent.,三、思考：下图中涂色部分占全图的几分之几？,我国的数学古书九章算术是世界上系统地叙述分数的最早著作，它所总结的分数运算方法和现代所用的方法是基本一致的。,一个物体、一些物体等都可以看作一个整体，把这个整体平均分成,若干份,，这样的,一份或几份,都可以用分数来表示。,一个物体:,如一个苹果、一张纸片、一块布,一个计量单位：,如1米、1千克、1平方米,由许多物体组成的,一个整体：,如一堆沙、全班同学、12面旗帜、6个苹果,单位“1”,1,1,1,1,2,2,3,3,4,5,6,8、读出下面的分数,并说出每一个分数的分数单位。,分数单位,1,6,1,7,1,1 5,1,18,1,100,1,6,2,7,11,18,7,100,4,15,1 2 1 1-4 5 9 3,图中的涂色部分能不能用下面的分数表示？,3,4,5,9,3,5,2,4,1,3,1,8,1,4,1,6,2,3,1,2,1,3,1,3,4,猜猜一共有几枝？,1,6,1,6,猜猜一共有几枝？,2,5,猜猜一共有几枝？,1,3,猜猜一共有几枝？,b,a,拓展练习：,1.把单位“1”平均分成a份，表示这样的 b份的分数是（），分数单位是,（）。,2.分数单位是 的分数你能写几个？,1,7,1,a,1,7,2,7,3,7,4,7,5,7,6,7,7,7,练一练,一、填空,1、把（）平均分成（），表示这样的（）或（）的数，叫做分数。,2、是把单位“1”平均分成（）份，表示这样（）份的数。,3.把5米长的绳子平均分成2份,这里单位“1”是(),每份是5米的(),4、,的分数单位是（），有（）个这样的分数单位，再添上（）个这样的分数单位就是自然数1,二、判断,1、把单位“1”分成几份,表示这样一份或几份的数叫做分数(),2、把单位“1”平均分成若干份,表示其中一份或几份的数,叫做分数单位(),3、1 和 单位“1”相等(),4、把单位“1”平均分成8份，取其中的5份，就是 八分之五 （）,三、思考：下图中涂色部分占全图的几分之几？,（）,（）,通过今天的学习，我们知道了在很早以前我们人类为了解决实际生产和生活中不能用整数表示结果的问题，就已经开始用分数来表示了，经过几千年的发展，我们对于分数的应用也变得更熟练更广泛。希望通过学习，我们每一位同学也能更多的了解分数，更好的学习分数知识。,小结:,再见,Friendship,the difference in China and the West,Chinese except friendships to be more lasting.,Different foundations for friendships.,Westerns expect friends to be independent.,Chinese usually expect more from their friends.,Chinese except friendships to be more lasting.,For Chinese a true friendship,endures throughout life changes,.Chinese are friends even if they havent spoken for 20 years.If you shared something at one time,then,all your life,you are friends.This is the best of guanxi(关系),the Wide Web that connects Chinese through time and space.So,we can say Chinese invented the,Internet,long before Bill Gates was born.,In North America,even the relationship in which people feel close and tell each other personal problems,may not survive life changes,such as moving to another city,graduation from a university or marriage.If the people do not see each other regularly,the relationship is likely to die.,Chinese usually expect more from their friends.,In the West,you can certainly ask a friend to do something with you,but you recognize that your friend,may say no,if he or she gives you as reason.,You would not expect a friend to drop everything to respond to a non-urgent,need such as shopping.Nor would you expect a friend to recognize and respond to your wishes without stating them.,A friend in China is someone who offers help without waiting to be asked,.There are few limits to what you can expect from a friend.You can feel free to tell your friend what he or she can or should do or help or please you.,Good friends are like stars.,You dont always see them,but you know they are always there.,