第 2 课 时 加减混合运算,复习:连加、连减(笔算),262538,701826,2,6,2,5,5,1,3,8,8,9,89,7,0,1,8,5,2,2,6,2,6,26,课前复习,复习:连加、连减(口算),12820,50306,42830,78188,78406,52128,40,14,20,52,32,48,课前复习,创设情境,2,新知探究,送给幼儿园33只,还剩多少只? 38 + 42 - 33 =,想一想先算什么,再接着往下算 。,47 只,8 0,2,试一试,“22 + 40”可以口算 。,62,1.,想想做做,50 - 26 + 49 45 + 38 - 24 44 + 52 37 74 - 27 + 36,=73,=59,=59,=83,2.,67,61,51,45,45,39,想想做做,3.计算下面各题,能口算的就口算。,351440,47168,833029,402615,61,55,81,24,想想做做,4.,想想做做,5.,(1)全班一共栽树多少棵?,36 + 28 64 棵,64 - 31 33 棵,(2)女生栽树多少棵?,想想做做,