加法交换律和结合律小学教学课件.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,2019/1/16,#,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,运算定律,第,1,课时 加法交换律和结合律,R,四年级下册,点击图片播放视频,2,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,3+4,7,4+3,7,你能将这两个算式合并成一个算式吗？,3+4,4+3,说一说你发现了它有什么特点？,3,3+4,4+3,都是加法。,加数不变。,结果一样。,加数的顺序调换了。,4,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,李叔叔今天一共骑了多少千米？,（,1,）从图中我们获得了哪些信息？,（,2,）我们要解决什么问题？,5,上午骑了,40,km,下午骑了,56,km,一共骑了多少千米？,列式：,40+56,96,56+40,96,说一说你发现了什么？,6,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,40+56 56+40,两个数相加，交换加数的位置，和不变。,这叫做,加法交换律,。,做一做,你能再举出几个这样的例子吗？,7,你能用自己喜欢的方式表示加法交换律吗？,甲数,+,乙数,=,乙数,+,甲数,+,=,+,a,+,b,=,b,+,a,我会用字母表示。,8,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,78+64,64+78,25+65,65+25,300+600,600+300,()+55,()+420,a,+999,999+,a,420,55,对,口,令,9,根据加法交换律填空。,300+600=600+,+65=65+35,78+,=43+,a,+12=12+,300,35,43,78,a,10,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,（,1,）从图中我们获得了哪些信息？,（,2,）我们要解决什么问题？,11,第一天,88,km,一共骑了多少千米？,第二天,104,km,第三天,96,km,方法一：,方法二：,88（10496）,88200,288,8810496,192,96,288,12,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,8810496,88,（,104,96,）,说一说等式两边有什么相同？有什么不同,再比较下面的两组算式，你发现了什么？,（,69+176,）,28,69,（,176,28,）,155,（1,45,207,）（,155,145,）,207,13,三个数相加，先把前两个数相加，或者先把后两个数相加，和不变。,这叫做,加法结合律,。,用符号表示：,（,a,+,b,）,+c,=,a,+,（,b+c,）,（,+,）,+,=,+,（,+,）,+,用字母表示：,14,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,口答,12+15+5,12+(15+_),243+146+54,243+(_+54),4037+(25+44),4037+25+_,a,+(,b,+,c,),a,+_+,c,5,146,44,b,15,根据加法结合律填空。,（,25+68,）,+32=25+,（,+,）,130+,（,70+4,）,=,（,130+,）,+,68,32,70,4,16,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,火眼金睛,1.,下面的算式分别运用了什么运算定律？,76+18=18+76,56+72+28=56+,（,72+28,）,31+67+19=31+19+67,24+42+76+58=,（,24+76,）,+,（,42+58,）,加法交换律,加法结合律,加法交换律,加法结合律,17,现学现用,2.,填一填：在下面的方框里填上合适的数。,96+35=35+,204+57=+204,（,45+36,）,+64=45+,（,+,）,560+,（,140+70,）,=,（,560+,）,+,96,57,36,64,140,70,18,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,（）,3.,下面的等式哪些符合加法交换律：,在（）打“”。,96+14=70+40,55+95=95+55,a,+30=40+,a,精挑细选,（）,（）,19,4.,计算下面各题，并用加法交换律验算。,133+647=,308+426=,780,1 3 3,+6 4 7,7 8 0,3 0 8,+4 2 6,7 3 4,验算：,6 4 7,+1 3 3,7 8 0,验算：,4 2 6,+3 0 8,7 3 4,734,大显身手,20,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,5.,养禽专业户王大伯家有鸡,108,只，鸭,187,只，鹅,92,只，王大伯家一共有家禽多少只？,108+187+92,108+92+187,200+187,387,（只）,答：王大伯家一共有家禽,387,只。,21,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,40+56 56+40,加法交换律：,两个数相加，交换加数的位置，和不变。,8810496,88,（,104,96,）,加法结合律：,三个数相加，先把前两个数相加，或者先把后两个数相加，和不变。,归纳小结,22,课堂小结,通过本节的学习，说一说你有哪些认识和收获。,23,课后作业,1.,课本,P19,，第,2,题；,2.,完成练习册本课时的习题。,24,