内容正文:
第 1 课时 旋 转(1)
第 5 单元 图形的运动(三)
人教版五年级数学下册
你还记得这是什么现象吗?
一、创设情境
风车是旋转现象
车杆是旋转现象。
荡秋千是旋转现象
2
Hiash... text has been truncated due to evaluation version limitation.
二、探究新知
问题:1.指针可以旋转吗?可以怎样旋转?
2.你能说说指针的位置是怎样变化的吗?
1
3
Hiash... text has been truncated due to evaluation version limitation.
12
1
2
3
4
5
6
7
8
9
10
11
O
从“12”到“1”,指针绕点O按顺时针方向旋转了30°;
4
Hiash... text has been truncated due to evaluation version limitation.
从“1”到“___”,指针绕点O按顺时针方向旋转了 60°;
从“3”到“6”,指针绕点O按顺时针方向旋转了 °;
从“6”到“12”,指针绕点O按顺时针方向旋转了 °;
问题:你能把这三句话补充完整吗?
5
Hiash... text has been truncated due to evaluation version limitation.
12
1
2
3
4
5
6
7
8
9
10
11
O
从“1”到“___”,指针绕点O按顺时针方向旋转了 60°;
3
6
Hiash... text has been truncated due to evaluation version limitation.
12
1
2
3
4
5
6
7
8
9
10
11
O
从“3”到“6”,指针绕点O按顺时针方向旋转了 °;
90
7
Hiash... text has been truncated due to evaluation version limitation.
12
1
2
3
4
5
6
7
8
9
10
11
O
从“6”到“12”,指针绕点O按顺时针方向旋转了 °;
180
8
Hiash... text has been truncated due to evaluation version limitation.
问题:1.在描述旋转现象时要注意些什么?
2.你能像这样描述指针位置的变化吗?
从“1”到“___”,指针绕点O按顺时针方向旋转了 60°;
从“3”到“6”,指针绕点O按顺时针方向旋转了 °;
从“6”到“12”,指针绕点O按顺时针方向旋转了 °;
90
180
3
9
Hiash... text has been truncated due to evaluation version limitation.
问题:右侧有车通过,车杆的位置会怎样变化?
左侧有车通过,车杆要绕点O1按顺时针方向旋转 90°;
右侧有车通过,车杆要绕点_____按________方向旋转___°;
逆时针
90
O2
三、巩固练习
10
Hiash... text has been truncated due to evaluation version limitation.
旋转的风车
11
Hiash... text has been truncated due to evaluation version limitation.
风车绕O点逆时针旋转( )°
O
90
12
Hiash... text has been truncated due to evaluation version limitation.
风车绕O点逆时针旋转( )°
O
180
13
Hiash... text has been truncated due to evaluation version limitation.
四、课堂小结
1.旋转的含义:物体绕着某一点或轴运动,这种运动
现象称为旋转。
2.旋转的三要素:旋转中心、旋转方向、旋转角度
14
Hiash... text has been truncated due to evaluation version limitation.
$