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1、角的初步认识教学设计课题:角的初步认识教学目标:知识 通过观察实物初步认识角,知道角的各部分名称,会用直尺画角,比较角的大小。能力 通过折角、画角等实际操作培养学生动手操作的能力。情感 通过实物抽象数学知识的过程,获得成功的体验,促使学生形成继续探索数学的决心。重 点:1、 认识角的各部分名称。2、初步学会用直尺画角。3、会比较角的大小。难 点:1、 学会用直尺画角。 2、能在情境图中找角。 3、会比较角的大小。教学环节:一。创设情境,激趣引入 ( 3 )分1、复习正方形、圆形、三角形、长方形。2、出示让学生说出他的名字,为什么这么叫它?3、揭示课题并板书:角的初步认识设计意图:根据学生的生活
2、经验,让学生感受角就存在于生活中。二。自主探索,感悟新知 ( 24 )分1、图形分类(有角和无角)。2、摸角(准备好的图形)。3、寻找身旁物体表面的角。5、抽象出数学中的角。(例1)一个顶点两条边组成角。6、练习(判断下面图形是不是角)。7、画角。(先让学生自由画,评价学生画的角,课件出示角的正确画法,师生共同画出规范的角。)小结:小小角,真简单, 一个顶点两条边。 画角时,要牢记, 先画顶点再画边。8、动手做角(利用学具圆形或硬纸条做角,展示学生做的角并请学生指出角)。9、比较大小。(出示两个角,一个边长一个边短,哪个角比较大呢?)学生利用刚才做的角,同桌互相讨论,探究如何比较角的大小?学生
3、发言,教师点评,之后总结:角的大小与边长无关,而是与角两边的开合大小有关。10、游戏:变变变。(学生利用手中的铅笔做出角,听教师口令把角变大或变小)设计意图:通过听-看-讲-想-做,使学生进一步地把角的形象化,把感性认识升华到理性,这一后循序渐进的原则,使学生从动手中发展思维,同时做角也发展了学生的创造思维。三。拓展练习,巩固新知。( 5 )分课本42页:第1题:检测学生是否掌握角的组成部分。第2题:检测学生是否能抽象出简单几何图形中的角。第3题:检测学生是否会比较角的大小,并强化:角的大小与角两条边的长短无关,而是与角的两边开合的大小有关。设计意图:检测学生掌握知识情况。四。课堂小结( 3
4、)分这节课你学到了什么?1、角的组成部分。2、如何画角。3、数出简单几何图形中有几个角。4、如何比较角的大小。设计意图:简单的回顾整理,形成基本的知识网络,整理学习思路,掌握角的初步知识,为以后的学习打好基础。QcWA3PtGZ7R4I30kA1DkaGhn3XtKknBYCUDxqA7FHYi2CHhI92tgKQcWA3PtGshLs50cLmTWN60eo8Wgqv7XAv2OHUm32WGeaUwYDIAWGMeR4I30kA1DkaGhn3XtKknBYCUDxqA7FHYi2CHhI92tgKQcWA3PtGZ7R4I30kA1DkaGtgKQcWA3P tGZ7R4I30kA1D
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