“三角形的内角和”是苏教版教材四年级下册第七单元的内容,是在学生认识了三角形的特征、了解了三角形三边的关系之后安排的。教材从学生已有知识和经验出发,呈现一副三角尺,引导学生通过计算每块三角尺3个内角的和,提出猜想:其他三角形的内角和也是180?吗?接着,引导学生自主经历“量→算”、“撕→拼”、“折→拼”等多样的验证过程,归纳出“三角形的内角和等于180?”的结论。这 “The inner corner of the triangle and ” is the content of the fourth unit of the fourth edition of the textbook of the Sujiao version, which is arranged after the students have understood the characteristics of the triangle and learned about the relationship between the three sides of the triangle. Textbook from the students have the knowledge and experience, showing a pair of trigonometry, and guide students to calculate the sum of each corner of the three trigonometry and make the conjecture: the other triangles and the angle is also 180?? Then, to guide students to autonomously experience “Quantity → count”, “tearing → spelling”, “folding → spelling” and so on. The conclusion is that “the internal angle of the triangle is equal to 180?”. This