(共11张PPT)
整理和复习
一、20以内退位减法的计算
11- 9
11- 8
11- 6
12- 8
12- 6
13- 8
13- 6
14- 8
14- 6
11- 4
11- 3
11- 2
12- 4
12- 3
13- 4
15- 8
15- 6
16- 8
17- 8
12- 9
13- 9
14- 9
15- 9
16- 9
17- 9
18- 9
11- 7
12- 7
13- 7
14- 7
15- 7
16- 7
11- 5
12- 5
13- 5
14- 5
竖着看你有什么发现?
十几-9
十几-8
十几-7
十几-6
十几-5
十几-4
十几-3
十几-2
11-8
12-8
13-8
14-8
15-8
16-8
17-8
11-9
12-9
13-9
14-9
15-9
16-9
17-9
18-9
12
11
13
14
15
16
17
18
11-7
12-7
13-7
14-7
15-7
16-7
11-6
12-6
13-6
14-6
15-6
11-5
12-5
13-5
14-5
11-4
12-4
13-4
11-3
12-3
11-2
11
12
13
14
15
16
17
11
12
13
14
15
16
11
12
13
14
15
11
12
13
14
11
12
13
11
12
11
8
8
8
8
8
8
8
7
7
7
7
7
7
6
6
6
6
6
5
5
5
5
4
4
4
3
3
2
从上到下
竖着看
被减数依次加1,
减数不变,
差依次加1。
=2
=3
=4
=5
=6
=7
=8
=9
9
9
9
9
9
9
9
9
=3
=4
=5
=6
=7
=8
=9
20以内退位减法表
=4
=5
=6
=7
=8
=9
=5
=6
=7
=8
=9
=6
=7
=8
=9
=7
=8
=9
=8
=9
=9
11-8
12-8
13-8
14-8
15-8
16-8
17-8
11-9
12-9
13-9
14-9
15-9
16-9
17-9
18-9
12
11
13
11-7
12-7
13-7
14-7
15-7
16-7
11-6
12-6
13-6
14-6
15-6
11-5
12-5
13-5
14-5
11-4
12-4
13-4
11-3
12-3
11-2
11
12
13
11
12
13
11
12
13
11
12
13
14
15
16
17
18
14
15
16
17
14
15
16
14
15
14
11
12
13
11
12
11
20以内退位减法表
8
8
8
7
7
7
6
6
6
5
5
5
4
4
4
3
3
2
从左到右
横着看
被减数不变,
减数依次少1,
差依次加1。
=2
=3
=4
=5
=6
=7
=8
=9
9
9
8
8
8
8
7
7
7
6
6
5
9
9
9
9
9
9
=3
=4
=5
=6
=7
=8
=9
=4
=5
=6
=7
=8
=9
=5
=6
=7
=8
=9
=6
=7
=8
=9
=7
=8
=9
=8
=9
=9
11-9
12-9
13-9
14-9
15-9
16-9
17-9
18-9
11-8
12-8
13-8
14-8
15-8
16-8
17-8
11-7
12-7
13-7
14-7
15-7
16-7
11-6
12-6
13-6
14-6
15-6
11-5
12-5
13-5
14-5
11-4
12-4
13-4
11-3
12-3
11-2
你们真棒!
你准行!
二、用20以内退位减法
解决问题
1、
解决问题
(3)你还能提出什么数学问题并解答吗?
问题: ?
解答: .
(1)小丽比小林多得了几朵?
( )
(2)小林比小丽少得了几朵?
( )
三、回顾小结
本节课复习了什么知识?
四、课外延伸
请用你最喜欢的方式(图形、文字等)表示出第二单元学习的内容。
可以出题考考自己……
谢 谢