三角形在平面图形中是最简单的图形,一切多边形都可以分成若干个三角形,因而它也是最基本的图形,是学习其他图形的基础。在此之前,学生已经系统认识过角,已经直观认识了三角形和其他一些简单的平面图形。因此,教学中需要找准学生的认知起点,创设条件,以学生动手活动为主线,在观察中发现,在动手中体会,在交流中理解。 Triangles are the simplest shapes in a plane graph. All polygons can be divided into several triangles. Therefore, it is also the most basic one and is the basis for learning other graphs. Prior to this, students had a systematic understanding of angular, has been intuitively aware of the triangle and some other simple graphic. Therefore, teaching students need to identify the cognitive starting point, the creation of conditions, the main line of student activities, found in the observation, in the hands of experience, understanding in the exchange.