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单击此处编辑母版标题样式,单击此处编辑母版文本样式,二级,三级,四级,五级,*,*,*,*,单击此处编辑母版标题样式,单击此处编辑母版文本样式,二级,三级,四级,五级,*,*,*,*,*,*,*,*,十几减,9,SJ,一年级下册,一,20,以内的退位减法,一共有多少条金鱼？,7,6,13,（条）,课后作业,探索新知,当堂检测,课堂小结,十几减,9,的计算方法,1,课堂探究点,2,课时流程,我买,9,个。,13,9 =,（个）,探究点 十几减,9,的计算方法,13,9 =,（个）,13,9 =,（个）,先减去,3,个，,再减去,6,个。,13,9 =,（个）,从,10,个里减去,9,个,13,9 =,（个）,9,加,（,4,）,得,13,，,13,减,9,得,4,。,13,9 =,（个）,你喜欢哪种方法？,4,先减去,3,个，,再减去,6,个。,从,10,个里减去,9,个,9,加,（,4,）,得,13,，,13,减,9,得,4,。,12,9 =,3,1,.,先圈一圈，再计算。,16,9 =,7,小试牛刀,（教材,P2,想想做做）,？个,15,个,？根,17,根,15,9 =,6,17,9 =,8,2,.,9,2 =,11,11,9 =,2,9,5 =,14,14,9 =,5,9,9 =,18,18,9 =,9,3,.,12,9 = 3,4,.,15,9 = 6,17,9 = 8,13,9 = 4,16,9 = 7,19,9 = 10,11,9 = 2,18,9 = 9,14,9 = 5,10,9 = 1,11,9 =,2,14,9 =,5,17,9 =,8,12,9 =,3,15,9 =,6,18,9 =,9,13,9 =,4,16,9 =,7,19,9 =,10,5,.,1,先圈一圈，再计算。,(1),14,9,(2),17,9,小试牛刀,（源于,典中点,）,圈一圈略,5,8,9,3,9,6,9,8,12,9,15,9,17,9,12,3,15,6,17,8,3,13,9,11,9,14,9,15,9,18,9,16,9,4,2,5,6,9,7,十几减,9,的计算方法：,破十法、平十法、想加算减法。其中，想加算减法最省时。,归纳总结：,（讲解源于,点拨,）,1.,3,夯实基础,（教材,P3,练习一）,9, ,12,12,9,3,2.,9, ,15,15,9,9, ,16,16,9,9, ,17,17,9,6,6,7,7,8,8,3.,9,11,15,13,17,9,18,14,16,12,2,4,6,8,9,7,5,3,4.,16,9,7 13,9,4 14,9,5 17,9,8,12,9,3 18,9,9,19,9,10 15,9,6,5.,15,9 6,14,9 5,6.,11,9,6,9,13,9,9,4,18,9,15,9,16,9,12,9,14,9,8,9,17,9,9,7,2,15,4,13,9,8,7,3,5,17,8,16,7.,13,9,8,18,9,9,17,9,7,8,7,9,12,0,15,6,有,11,支蜡烛，吹灭了,9,支，还有多少支亮着？,8.,（支）,11,9 2,9.,树上原来有,13,只猴，下来,3,只。树上还剩多少只？,（只）,13,3 10,13,9 4,4,18,9,2,7,8,9,10,6,9,12,9,8,19,9,1,4,7,9,易错辨析,（选题源于,典中点,）,辨析：两步计算时，数字看错，符号看错，得数写错等原因造成,7,6,7,11,9,2,
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