一、导入新课(一)请你照我这样做。师生同做:拿出活动角(重合状),开始旋转角的一条边,使之成锐角、直角、钝角。边做边引导学生思考:旋转成了什么角?(二)拼摆图形,引入“三角形的认识”。让学生在活动角的两边上各取一点,使角的两边分别表示一条线段。再让学生增加一根硬纸条,任意和已知角拼成一种图形。(多媒体演示:屏幕上显现出学生拼摆的图形。(见下图)) First, the introduction of a new lesson (A) Please follow my example. Teachers and students to do: Take out the corner of activity (coincidence), began to rotate the edge of an edge, so that the acute angle, right angle, obtuse angle. To do while guiding students to think: what angle into the rotation? (B) splicing graphics, the introduction of “triangular understanding.” Have students take a little bit on each side of the corner of activity so that the two sides of the corner each represent a line segment. Let students add a piece of cardboard, arbitrarily and known angle spell into a graph. (Multimedia Presentation: The picture showing the student's put together on the screen (see below))