一、教学任务分析教材分析:三角形内角和定理是新人教版八年级数学第十一章的重要内容,也是“图形与几何”必备的知识基础。它从“角”的角度刻画了三角形的特征。三角形内角和定理的探究体现了由实验几何到论证几何的研究过程,同时也说明了证明的必要性。三角形内角和定理的证明以平行线的相关知识为基础。定理的验证方法——剪图、拼图,不仅可以说明证明的必要性,而且也可以从中获得添加辅助线的思路和方法。定理的证明思路是得出 First, the teaching task analysis Textbook analysis: Triangular interior angle and theorem is the eighth chapter of the New PEP mathematics eleventh chapter is an important part, but also “graphics and geometry,” the necessary knowledge base. It characterizes the triangle from the “angle” perspective. The study of interior angles and theorems of triangles embodies the research process from experimental geometry to argument geometry, and also illustrates the necessity of proof. Proof of interior angles and theorems of triangles is based on knowledge of parallel lines. Theorem validation methods - cut charts, puzzles, not only can prove the need for proof, but also can get ideas and methods to add auxiliary line. The proof of the theorem is drawn