第5课时乘法分配律.pptx

,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,人教,版四年级数学下册,乘法分配率,授课教师：岳阳经济技术开发区北港小学 易琴,授课班级：岳阳,经济技术开发区北港小学,四（,6,）班,在,任意填上一个相同的数。,57,+43,=,？,激趣导入,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,一共有,25,个小组，每组里,4,人负责挖坑、种树，,2,人负责抬水、浇树。,探讨新知,一共有多少名同学参加植树活动？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,（,4+2,）,25,425+225,一共有多少名同学参加植树活动？,答：一共有,150,名,同学参加植树,活动,。,625,150,（名）,100+50,150,（名）,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,（,4+2,）,25,425+225,说一说,1.,你,能,用乘法的意义解释下为什么相等吗？,3.,观察这些等式，等式左边有什么相同点？,等式右边有什么相同点？,2.,你还能举出像这样的等式吗？,4.,你,发现了,什么？,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,这叫做,乘法分配律,。,两个数,的和,与一个数相乘，可以先把它们与这个数,分别,相乘，再相加。,（,4,+,2,）,25,4,25,+,2,25,用字母表示是：,（,a,+,b,）,c,a,c,+,b,c,a,（,b+c,）,_,a,b+a,c,状元成才路,状元成才路,状元成才路,状元成才路,小 结,两个数,的,和,与,一个数相乘，可以先把它们与这个数,分别,相乘，再,相加,，,得数不变,。这,叫做,乘法分配律,1.,下面哪些算式是正确的？正确的画“”，错误的画“,”。,56,（,19+28,）,=5619+28,（）,32,（,73,）,=327+323,（）,6464+3664=,（,64+36,）,64,（,）,（,40-4,）,25,=40 25-425,（）,巩固提高,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,2.,计算下面各题，怎样简便怎样计算。,（,8+4,）,25,26,32+26,68,3.,在任意填上一个相同的数。,57,+43,=,？,a,b,+,a,c,a,（,b,+c,）,(,57+43,),课堂小结,通过本节的学习，说一说你有哪些认识和收获。,课后作业,1.,课本,P27,，第,5,题,；,2.,完成练习,册,22,页的,习题。,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,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,状元成才路,7560+4560,=60,（,75+45,）,=60120,=7200,（元）,答：一共花了,7200,元钱。,5.,李阿姨购进了,60,套这种运动服，花了多少钱？,