小学数学西南师大六年级上册四比和按比例分配《比的意义》 PPT

在日常生活和工作中，常常把两个数量进行比较。张丽用的时间是李兰的几倍？5÷4=张丽和李兰所用的时间比是5比4。同类量的比李兰用的时间是张丽的几分之几？4÷5=李兰和张丽所用的时间比是4比5。在日常生活和工作中，常常把两个数量进行比较。张丽从家到学校每分钟走多少米？240÷5张丽所行路程和时间的比是240比5。不同类量的比李兰从家到学校每分钟走多少米？200÷4李兰所行路程和时间的比是200比4。两个数相除又叫做两个数的比。..（1）几比几怎样写、怎样读？（2）比的书写形式有几种？（3）比的各部分名称是什么？（4）怎样求比值？自学提示比的读法﹑写法。“”是比号，读作“比”两个数的比可以写成一般形式和分数形式两种5÷4可以写成5﹕4或都读作“5比4”5︰4

前项

比号

后项比值如何去求一个比的比值呢?比的各部分名称:=5÷4=

同桌讨论：比的前项、后项和比值分别与除法、分数之间有怎样的联系？名称联系区别比除法分数比号（﹕）前项后项比值除号（÷）被除数除数分子分数值分母分数线（－）商一种关系一个数一种运算（相当于）

除法中的除数和分数中的分母不能为“0”，那么比的后项呢？比的后项也不能为“0”。说说你有何收获。填空：（1）小敏和小亮在文具店买同样的练习本。小敏买了6本，共花了1.8元。小亮买了8本，共花了2.4元。小敏和小亮买的练习本数的比是(

)︰()，比值是（）；花的钱数之比是(

)︰（），比值是（）。681.82.4判断对错我能行。（1）小明身高150厘米，爸爸身高1.7米，小明与爸爸身高的比是150︰1.7（）（2）把1克盐溶于20克水中，盐与盐水重量的比是1︰20。（）（3）甲数是乙数的3/5，则甲数与乙数的比是3﹕5。（）××√求出下面各个比的比值：3﹕121.5﹕2.4﹕思考：

3︰（）=24

（）︰8=0.5谢谢！Pleasewritedownofasloganforavisionofacompanyinshortly.Pleasewritedownofasloganforavisionofacompanyinshortly.Pleasewritedownofasloganforavisionofacompanyinshortly.Pleasewritedownofasloganforavisionofacompanyinshortly.Vision01Vision03Vision02Vision04CompanyLOGOClicktoedittitlestyleClicktoedittitlestyleTitleinhereThemeGalleryisaDesignDigitalContent&ContentsmalldevelopedbyGuildDesignInc.DescriptionofthecontentsDescriptionofthecontentsDescriptionofthecontentsDescriptionofthecontentsTitleinhereTitleinhereTitleinhereClicktoedittitlestyleContents01Contents02Contents03Contents04Contents05Contents060%20%40%60%80%100%18.5%17.5%8.7%23.6%63.6%84.3%ThemeGallery

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