第四单元

U4、Line —— parallel and intersecting............ in traffic

四、交通中的线——平行与相交

Lesson One

第一课

What questions can you ask?

你能提出什么问题?

Cooperative exploration

合作探索

What is the position relationship of several groups of straight lines in the diagram?

图中的几组直线有怎样的位置关系?

I drew these lines down and studied them.

我把这几组直线画下来研究。

Can you classify these groups of straight lines?

你能给这几组直线分类吗?

The two lines in 4 and 5 intersect and can be divided into one class.

④和⑤中的两条直线相交了，可以分为一类。

two straight lines in ①、③ and 6 do not intersect and can be divided into one class.

①、③和⑥中的两条直线没有相交，可以分为一类。

Two straight lines in 2...

②中的两条直线....

Two straight lines that do not intersect in the same plane are parallel to each other, one of which is the parallel line of the other line.

在同一平面内不相交的两条直线互相平行，其中一条直线是另一条直线的平行线。

Can you draw a set of parallel lines?

你能画出一组平行线吗?

I use two strokes.

我用两支笔画。

I draw with a ruler.

我用直尺画。

I draw on the idea map.

我在点子图上画。

I draw with two rulers

我用两把直尺画

Lesson two

第二课

What questions can you ask?

你能提出什么问题?

Cooperative exploration

合作探索

Can you classify the following groups of intersecting lines?

你能给下列几组相交的直线分类吗?

①④⑤ two straight lines intersect, the angles are right angles.

①④⑤中的两条直线相交时，所成的角都是直角。

Two straight lines in 2,3...

②③中的两条直线....

When two straight lines intersect at right angles, the two lines are perpendicular to each other, one of which is the vertical line of the other line, and the intersection point of the two lines is called the vertical foot.

两条直线相交成直角时，这两条直线互相垂直，其中一条直线是另一条直线的垂线，两条直线的交点叫作垂足。

Can you draw two lines perpendicular to each other?

你能画出两条互相垂直的线吗?

I draw it with a triangle.

我用三角尺画。

I use a protractor.

我用量角器画。

I draw with two ruler.

我用两把直尺画。

I draw on the idea map.

我在点子图上画。

The vertical line of any straight line can be drawn by using the triangle plate.

利用三角板，可以画出任意一条直线的垂线。

Can you draw the vertical line of this line over A points?

你能过A点画出这条直线的垂线吗?

Lesson three

第三课

Why the tunnel?

为什么要修隧道呢?

What more questions can you ask?

你还能提出什么问题?

Cooperative exploration

合作探索

Why the tunnel?

为什么要修隧道呢?

I'll try to paint...

我来画画试试......

I found the shortest line between two points.

我发现两点之间线段最短。

The length of a segment between two points is the distance between two points.

两点之间线段的长度就是两点间的距离。

The tunnel can be repaired without detour.

修隧道可以不绕路。

From a point outside the line A draw several different lines to intersect with the line, measure the length of these lines, what can you find?

从直线外一点A画几条不同的线段与这条直线相交，量量这些线段的长度，你能发现什么?

The shortest vertical one.

垂直的那条最短。

The vertical line from a point outside the line to this line is the shortest, and its length is called the distance from the point to the line.

从直线外一点到这条直线所画的垂直线段最短，它的长度叫作点到直线的距离。