教学片断:师:同学们,我们一起学习了量角的方法,很复杂,有没有兴趣把量角的过程编成儿歌,边唱歌边量角呢?生:有。(众生一起回答,声音特别响亮。)师:用量角器量角时,第一步干什么?生1:把量角器的中心点与角的顶点重合。生2:可以说成:中心顶点先重合。生3:中心对准角顶。生4:中心 Teaching pieces: Teacher: Classmates, we learn the method of measuring the angle, is very complex, is there any interest in the process of measuring the amount of children's songs, while singing the amount of angle it? (All sentient beings answered with a loud voice.) Teacher: What is the first step when using a goniometer? Health 1: The center of a protractor coincides with the vertex of a corner. Health 2: Can be said to be: the center of the first coincidence. Students 3: Center at the top of the corner. Health 4: Center