沪教版一年级上：3.5 加减法（二）——退位减法 课件（13张）

请你算一算
11-1= 3+7= 10-3=
15-5= 2+8= 10-9=
12-2= 6+4= 10-5=
10
10
10
10
10
10
7
1
5
说说怎么算
8 + 6 =
9 + 3 =
①
②
①
②
12
8 + 2 = 10
10 + 4 = 14
14
9 + 1 = 10
10 + 2 = 12
加减法（二）——退位减法
试一试：
14 – 5 =
仔细观察：
14 – 5 =
① 14 – 4 = 10
② 10 – 1 = 9
① 10 – 5 = 5
② 5 + 4 = 9
9
1
2
3
0
19
18
5
6
8
4
10
11
12
9
14
15
16
13
17
7
20
14 – 5 =
① 14 – 4 = 10
② 10 – 1 = 9
9
试一试：
想一想：
13 – 6 = 7
11 – 6 = 5
① 13 – 3 = 10
② 10 – 3 = 7
① 11 – 1 = 10
② 10 – 5 = 5
减数都是6，为什么分拆得不一样呢？
13 – 6 = 7
11 – 6 = 5
① 13 – 3 = 10
② 10 – 3 = 7
① 11 – 1 = 10
② 10 – 5 = 5
15 – 6
12 – 6
5
1
2
4
想一想：
用你喜欢的方法进行计算：
14 – 6 =
12 – 3 =
①
②
①
②
13 – 7 = 7
① 13 – 5 = 9
② 9 – 2 = 7
我来做小老师：
×
13 – 7 =
① 13 – 3 = 10
② 10 – 4 = 6
6
11 – 4 = 7
① 10 – 4 = 6
② 6 + 1 = 7
√
我来做小老师：
×
14 – 9 =
① 10 – 9 = 1
② 4 + 1 = 5
3
14 – 9 = 3
① 10 – 9 = 1
② 4 - 1 = 3
我来做小老师：
看看你能得几颗★：
17 – 9 =
14 – 7 =
★
★
★
★
①
②
①
②
①
②
①
②