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,2018/8/19,#,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,小学数学四,年级下册,运算定律,第,1,课时,xxxxxxxxxx,xxx,加法交换律,和结合律,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,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？,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,2,3+4,4+3,都是加法。,加数不变。,结果一样。,加数的顺序调换了。,3+44+3都是加法。加数不变。结果一样。加数的顺序调换了,3,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？,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,4,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？,上午骑了40 km下午骑了56 km一共骑了多少千米？列式：,5,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？,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,6,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。,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,7,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,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,8,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,根据加法交换律填空。300354378a,9,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？,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,10,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,第一天 88 km一共骑了多少千米？第二天 104 km第三,11,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,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,12,三个数相加，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：,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。,13,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,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,14,根据加法结合律填空。,（,25 + 68,）,+ 32 = 25 +,（,+,）,130 +,（,70 + 4,）,=,（,130 +,）,+,68,32,70,4,根据加法结合律填空。（ 25 + 68 ）+ 32 = 25,15,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,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,16,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,现学现用2.填一填：在下面的方框里填上合适的数。965736,17,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,（ ）,（ ）,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,18,4.,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,4.计算下面各题，并用加法交换律验算。780 1,19,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。,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,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,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,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,21,课堂小结,通过本节的学习，说一说你有哪些认识和收获。,课堂小结通过本节的学习，说一说你有哪些认识和收获。,22,课后作业,1.,课本,P19,，第,2,题；,2.,完成练习册本课时的习题。,课后作业1. 课本 P19 ，第 2 题；,23,再见！,再见！,24,