《画角》教学案例2600字 《画角》教学案例教学内容:人教版新课标四年级上册P42例4教学目标:1、使学生学会按给定的度数画角,形成画角的技能,初步培养学生的作图能力2、理解、掌握画角的步骤,能正确地画出给定度数的角 教学重难点:1、学会按给定度数画角2、理解、掌握画角的技能教学过程:一、复习旧知,设疑导入1、复习师:我们已经学过角的度量和角的分类你们学会了吗? 生:学会了师:很好用你们的量角器度量出所准备的两个角的度数,并说出它们是哪一类的角?2、导入新知师:谁来汇报下你所度量的度数,并说出是哪一类的角? 生1:∠1=40°,是锐角生2:∠2=116°,是钝角师:说的非常正确大家都能用量角器度量出角的度数,如果老师给一个度数,你们能画出这个角吗?这节课我们就共同来研究怎样去画已知度数的角,有没有信心学会?生:有板书课题——画角)(使用工具量出角的度数,既复习了旧知,又为学生利用工具自主探究、合作交流学习新知在方法上起到了迁移铺垫作用二、自主学习,获取新知1、用量角器画角师:请同学们打开课本P42,自学P42的画角步骤,根据你所理解的去尝试画一个65°的角,可以与同桌合作完成。
教师巡视) 师:谁来说说你是怎么画的?生1:先画一条线,再把量角器的中心对准这条线的端点,师:有端点,所以我们刚才画的应该是射线,好,你接着说 生2:零刻度线对准射线,然后找到65°,点一个点,最后再把这个点和射线的端点连起来大胆地放手让学生借助工具进行自主学习,小组、集体交流,为他们提供了足够的探究时间和空间师:说的非常的好表扬)师:现在老师来演示一次边说边画,并提醒学生,习惯将射线画成水平的)师:知道怎么画了吗?你们听明白了吗?生:知道了,明白了2、练习画角师:那下面请同学们自己在草稿纸上完成P42做一做T2学生操作,教师巡视,同时叫两位学生板演)师:谁来说说画角最关键是什么?生1:零刻度线要与射线重合生2:量角器的中心也要与射线的端点重合生3:还要看清量角器的里圈外圈师:你的提醒真不错,也就是说要看清零刻度线指着黑板上的65°角)如果老师说这个是115°的角,你们不用量角器能判断它是否正确吗?生:能,因这115°是钝角,而65°的角是锐角真不错,能利用角的特征来判断,所以,我们画完角后,自己要利用角的特征判断下引导学生在画的过程中思考注意的问题,并提醒学生养成检查的习惯,有效促进了对画法的深刻理解与掌握。
3、利用三角板画角师:同学们都学会用量角器画一个已知度数的角,真聪明!但老师不用量角器也能画出一个规定度数的角,你们知道怎么画吗? 生:用三角板师:你们太聪明了,和老师想到一块了教师演示画一个60°的角)师:需要用量角器检验下吗?生:不用,老师刚才是用三角板中的60°的角画出来的,它肯定是60°师:老师发现你们越来越聪明了那你们能用三角板画一个45°的角吗?生:能师:同学们画得太快了,实在太简单了那老师加大难度,有信心挑战吗?生:有师:老师有个问题,想请同学们帮忙我想画一个15°的角,但没有量角器,只有一副三角板,你能不能画出来?先静静地思考一下,也可以和同桌商量一下思考片刻)生1:我先画一个30°的角,然后再把它从中间分开 师:从中间分开?这中间在哪?你怎么找?(又思考片刻)生2:先画好30°的角,然后再在三角板里面的位置点个点,再这个点和角的顶点连起来就是15°的角了师:会去思考,不错我们来看看,刚才画的60°角和45°角,你有没有想到什么?(思考片刻)生3:60°减去45°就是15°师:有新发现了生4:我知道了,用三角板先画一个60°的角,再用45°的角的顶点和一条边对齐,画一个45°的角,剩下来的那个角就是15°的角。
师:其他同学听明白了吗?我们请他到黑板上来画给我们看看 (该生在黑板上演示)师:除了这个方法之外,还有什么方法也能画出15°的角? 生:45°—30°=15°师:请同学们用三角板上自己喜欢的角在草稿纸上画一画15°的角学生操作,教师巡视,个别指导)师:用一副三角板还能画出哪些角?生1:90°生2:105°,45°+60°=105°生3:45°+30°=75°生4:90°+60°=150°??师:还有很多,现在我们就不一一例举了刚才是谁帮我们想出了这两个方法的?(掌声表扬)(教师通过借助一副三角板画出60°的角,并提出画一个15°的角,这样有效地激发了学生的思维,让学生知道了三角板可以画出一些特殊的角三、总结师:这节课,你学会了什么?生:我学会了用量角器和三角板画角师:回忆一下,是如何画的?有哪些步骤?(生说师板书)① 先画射线② 两个重合③点点连接④再画射线⑤标上度数三角板: 拼、减四、课堂作业用课堂作业本完成P43 T2《画角》教学反思《画角》是人教版新课标四年级上册P42的内容本节课的重点是让学生学会如何画一个已知度数的角,难点是让学生理解并掌握画角的技巧及用三角板画一些特殊的角首先,这节课我采用的是自主学习的教学方式。
先让学生开书自学画角的步骤,然后尝试去画出一个65°并说出自己是怎样画的,最后通过老师正确的演示画角的过程并说出画角的关键之处通过这三步,使学生牢固的记住了画角的过程接着通过练习画75°和105°的这两个角,更清晰地让学生知道画角时应该注意量角器的内个圈的刻度其次,我提出不用量角器也能画出一个已知度数的角,这样使学生有了好奇心,让学生想到用三角板也能画角,并演示用三角板画一个60°的角最后,我又抛出一个问题:“没有量角器,怎样画一个15°的角?可以同桌合作”,再次把学生的思维给调动起来,并让学生学生与他人合作学习的良好习惯本节课也存在着不足之处如:在让学生画15°的角时,没有去巡视下面学生画的情况,还有没有更清晰的讲解画的过程及注意事项因此,在以后的教学中,我会更加的努力去学习,去备课,更好的上好每一堂课第二篇:情景教学案例 4600字Examples of teaching grammarExample 1 presenting the passive voice: simple past tenseThe text below is given to the students to read. They are given the following questions to answer while reading:1. Can you explain the word “jeans” or give the Chinese equivalent?2. What do we call the material from which jeans are made?3. What do we call the person who cuts material for making clothes?4. What do we call the machine that sews clothes?5. What do we call the people who sew clothes with a machine?6. What do we call the person who controls the workers in a factory?Mr. Xu is a very successful businessman. He runs a big jeans business. This is how his business starts.First a plot of land was bought and a small factory was built on it. Then six sewing machines were bought and an amount of denim material. Then three cutters and six machinists were employed, and a foreman, a secretary and two salesmen were appointed. The jeans were designed by Mr. Xu himself and the design was given to the cutters. The material was cut by the cutters and then sewn by the machinists. The final product was inspected by the foreman. Then the jeans were sold by the salesmen. Soon, more workers were employed and two new factories were opened.Example 2 presenting the present conditionalIf I were…..If I were a treeI would let all tired people lean against meIf I were a peaMost tasteful to people I would beIf I were teaI would bring all sweetsIf I were a seaMost powerful I would try to beExample 3 presenting the past conditionalBelow, you can see a song that has been specially written by a teacher in order to teach his students the past conditional tense. He calls it “the 3rd conditional song”If I had listened to my teacherI wouldn’t have failed that testIf I had listened to my teacherI could have been one of the bestIf I had listened to my teacherI would have been better todayIf I had listened to my teachersI would have got a better jobIf I had listened to my teachersI wouldn’t have been such a yobIf I had listened to my teachersI would have been richer today.(one - two)So hear one thingAs you hear me sing -----Listen to what your teachers say.1) Did the singer listen to his teacher?2) What was the re。