课件13张PPT。闯关游戏9+( )=109+( )=119+( )=129+( )=139+( )=149+( )=159+( )=169+( )=179+( )=18123456789
你发现哪些数学信息?你能提出什么数学问题?买铅笔加与减
还剩几枝铅笔?一根一根的减分开减再加先减一部分再减一部分9 + 6 = 1515 – 9 = 6想加法算减法
运用计数器计算4710 – 9 =
11 – 9 =
12 – 9 =
13 – 9 =
14 – 9 =
15 – 9 =
16 – 9 =
17 – 9 =
18 – 9 =
19 – 9 =
20 – 9 =1234567891011你能发现什么?10 – 9 = 1 12 – 9 = 3
15 – 9 = 6 18 – 9 = 9
13 – 9 = 4 11 – 9 = 2
16 – 9 = 7 14 – 9 = 5
20 – 9 = 11 17 – 9 = 8
19 – 9 = 10
我的发现打乱顺序你又能发现什么?为什么?