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教学“圆的认识”,应使学生掌握圆的特征,会用工具画图,理解直径与半径的相互关系,认识圆是轴对称圆形。但教材中引入的实例,容易使学生产生错觉,把和圆混起来。因此,教学中应注意抓好下述四个问题。一、用实物或实物图引出圆的概念,把圆和圆面区别开。引入圆的概念,应结合教材分两步进行。第一步:先由教师举出硬币、钟面,车轮等圆形的物体,让学生认识它们的表面是圆形的面。然后再启发学生列举实际生活中存在的圆面的例子。这时学生会继续举出钮扣、饼、飞盘…….至此学生初步建立了圆的表象。接着教师又提出:男生玩的铁环、篮球架
Teaching “round understanding”, should enable students to grasp the characteristics of the circle, will draw a tool to understand the relationship between diameter and radius, the circle of knowledge is circular axisymmetric. However, the introduction of examples in the textbook, easy to make students illusion, the confusion and round. Therefore, teaching should pay attention to the following four questions. First, the use of physical or physical map leads to the concept of a circle, the circle and round face to distinguish. The concept of the introduction of the circle should be combined with the textbook in two steps. The first step: first by the teacher cited coin, clock face, wheels and other round objects, so that students recognize that their surface is a circular surface. And then inspire students to enumerate the real examples of the existence of the circle of life. Then students will continue to give buttons, cakes, frisbee ... ... So far the students initially established a round appearance. Then the teacher put forward: boys playing iron ring, basketball stand