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三角形的面积计算,是在学生已经认识三角形的特点,掌握了平行四边形的面积计算的基础上进行教学的。这一节课的教学,要使学生初步掌握三角形面积的计算公式,懂得公式是怎样推导出来的。为了在课堂教学中摸索如何培养学生的能力,让学生自己探索掌握知识的途径,下面提出三种不同的教学方案,供教师参考。第一种方案先讲用数方格的方法求三角形面积。让学生数出画在方格板上的一个三角形占有多少方格(不满一格的,都按半格计算),这个三角形的面积即是多少平方厘米。教师说明用数方格的方法求三角形面积很不方便,也不够准确,应当学会用计算的方法来求三角形的面积。
Calculation of the area of the triangle is based on the fact that students have recognized the characteristics of the triangle and mastered the calculation of the area of the parallelogram. The teaching of this lesson, to enable students to initially grasp the formula of the triangle area, understand how the formula is derived. In order to explore how to cultivate students 'abilities in class teaching and to let students explore their own ways of acquiring knowledge, three different teaching schemes are proposed below for teachers' reference. The first program first talk about the method of using a few squares triangle area. Have the student count the number of squares (less than one grid, calculated according to a half grid) of a triangle drawn on the square grid, the area of the triangle is the number of square centimeters. The teacher explained that with a few square method to find the triangle area is very inconvenient, not accurate enough, should learn to calculate the triangle area.