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在七年级“三角形内角和”的教学中,我指导学生通过自己动手实践、自主探索、合作交流数学活动体验,让他们真正理解和掌握了基本的数学知识、数学思想和方法,从而提高了学生的学习能力.具体做法如下:一、探究前准备1、让学生准备好剪刀、胶水,用硬纸剪好的锐角、直角、钝角等三角形(参照图1)若干个,三角板、量角器、铅笔等实验工具.2、组织4—5个学生为一小组,便于在遇到较难解决的问题时进行讨论.3、思考解决下列问题:①什么是平角?平角是多少度?②如果几个角的和组成的大角,顶点、两边都在同一直线上,这个角是不是平角?③想一想,到目前为止可用什么方法得知三角形的内角和等于180°?如何解决?二、探究过程探究三角形内角和定理可采用以下三种方法进行:
In the seventh grade, “Inside the Triangle and ” teaching, I guide students through their own hands-on practice, exploration, cooperation and exchange of mathematical experience, so that they really understand and mastered the basic mathematical knowledge, mathematical ideas and methods to improve First, to prepare for the inquiry 1, let the students ready for scissors, glue, paperboard cut with a good angle, right angle, obtuse triangle (see Figure 1) several, set square, protractor, Pencil and other experimental tools .2, organize 4-5 students for a small group, easy to discuss in the face of difficult problems to solve.3, think and solve the following questions: ① What is the angle? Angle and the composition of the large angle, the vertex, both sides are in the same line, the angle is not a flat angle? Think about what methods can be used so far to know the internal angle of the triangle and equal to 180 °? How to solve? The process of triangulation triangle and theorem can be used in the following three ways: