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1、20以内的退位减法 十几减9,班级：一（1）班,复习：,9+2=5+9=9+5=3+9=9+3=6+9=9+6=11 14 12 15/1 4 2 5,11,14,14,12,12,15,15,10,10,10,10,9+6=,9+7=,9+3=,15,16,12,9+8=,17,9+4=,13,9+5=,14,9+2=,11,9+（）=12,3,要有11人来踢球，现在来了9人。你能提出什么问题？,11 9=,2,10,1,1,2,109=1,11=2,想：,21,119=,2,想：,9加（2）等于11。,21,119=,2,想：,9加（2）等于11。,11 9=,2,10,1,1,2,109
2、=1,11=2,你喜欢哪一种方法？,有 15 个气球，卖了 9 个。,还有几个?,6,摆一摆，算一算。,10-9=1；1+()=()。,9+()=12；12-9=()。,3,你喜欢哪种方法？还可以怎样计算？,3,3,2,3,跳木桩,=,给、或=找个家。12-9 4 11-9 11+913-3 13-9 18-9 9,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,8,3
3、,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,189,179,129,119,169,139,8,3,7,5,2,4,6,159,149,179,129,119,169,139,189,树上原来有14只小鸟，,飞走了9只小鸟。,原来有1个松果，小松鼠搬走了9 个。,14-9=5（只）,15-9=6（个）,11 9=2,12 9=3,13 9=4,14 9=5,15 9=6,16 9=7,17 9=8,18 9=9,11 9=212 9=313 9=414 9=515 9=616 9=717 9=818 9=9总结：十几减9就得几加1.,
