一年级数学下册二20以内的减法2.312减几课件1冀教版.ppt
11-3=,11-5=,11-9=,11-4=,11-8=,11-6=,8,6,2,7,3,5,11-7=,4,11-10=,1,12 减几,看图列式计算。,去掉5块,还剩几块?,列式: - =( ),12,5,因为5+7=12, 所以12-5=7。,从10块中去掉5块还剩5块,5块加2块是7块。,2,10,5,7,破十法,想一想:,如果去掉6块怎样算?,算一算,12-7=,5,想:7加( )得12。,5,12-10=,想:10加( )得12。,2,12-3=,9,想:3加( )得12。,9,2,12-6=,,,2,,,,10,4,6,10,7,9,2,10,5,7,2,算得巧,算一算:,练一练:,.,.,12朵花减去9朵还有几朵?,12-9=,3,算一算,算一算,有12颗星,拿去5颗星。还剩几颗?,12-5=,7,想:5加( )=12,7,12只兔子减去9只还剩几只?,12-9=,3,想:9加( )=12,3,.,动手操作,我能行。,请把12根小棒分成两堆,每分一次你能说两个减法算式吗?试试看。,,,,,=,,,,,=,