平行与垂直说课稿
四年级数学
上册
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《垂直与平行》说课稿
六枝特区第一小学 郝云桂
一、说教材
《垂直与平行》是人教版《义务教育课程标准试验教科书数学》四年级第四单元《平行四边形和梯形》的第一课时,直线的平行与垂直是在学生认识了点和线段以及射线、直线的基础上安排的,也是进一步学习空间与图形的重要基础之一。垂直与平行是同一平面内两条直线的两种特殊的位置关系,在生活中有着广泛的应用,生活中随处可见平行与垂直的原型。学生的头脑里已经积累了许多
表
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象,因此教学中让学生在具体的生活情境中,充分感知平面上两条直线的平行和垂直关系。本课时主要解决平行和垂直的概念问题。
二、 说教法
本节课我依据学生已有的生活经验和知识为基础,从学生出发,以《数学课程标准》的新理念为指导,遵循学生的认知规律,由生活实例引入,通过猜测、动手画线、图形反馈使学生系统深入地掌握知识,以及运用分类、观察、讨论等方法以拉近学生与知识的距离,从而揭示出平行与垂直的概念,最后加以巩固、提高与应用。
本节课的教学力求创造性地使用教材,在课堂教学
设计
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中力求体现1.注意创设生活情境,,使数学学习更贴近生活。2.让学生通过动手操作,自主探索和合作交流的学习方式,亲身体验,自主完成对知识的建构。3.努力创设新型的师生关系,让学生主动参与,快乐学习,sun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, the direct punishment 0.5-10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal injury accident occurs, the direct punishment 500-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 500-1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specifications, serial number a 1 GB3323-2005 steel fusion welded butt joints, welding engineering-Ray lighting and quality rating of 2 GB11345-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4
教师适时给予鼓励,让课堂焕发生命活力。
三、说教学目标
1、认知目标:让学生结合生活情境,通过自主探究活动,初步认识平行线,垂线。
2、技能目标:使学生经历从现实空间中抽象出平行线的过程,培养空间观念。
3、情感目标:在数学活动中让学生感受到数学知识在生活中的真实存在,增强学生对数学的兴趣,养成独立思考的习惯,培养用数学的意识。
四、说教学重难点
教学重点:感知平面上两条直线的平行、垂直的关系,认识两线平行垂直。
教学难点:学生通过自主探究和合作交流建立垂直与平行的空间观念。
五、说教学过程:
(一)创设情境,导入新课
晚上,吃过晚饭小明在收拾碗筷时,不小心把两根筷子掉在地上了,如果用两根筷子表示两条直线。请同学们发挥想象力猜测一下:两根筷子落在地上可能会形成怎样的图形,请同学们动手画一画。(设计意图:创设生活中的情境,引入新课,便于沟通数学与生活的联系,有利于激发学生的学习兴趣和欲望。)
(二)引导探索,感知特征
-criticism and 50 1000, who is directly responsible for the accident responsibility, give notice of-injury accident occurs, the direct punishment 500p, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal 10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadershi-e direct punishment 0.5inistrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, thg adm~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerninfined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1 b unitnstruction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the jon. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, cosun exposure measures, responsibilities of team a fine of 50 Yuag engineering code for construction and acceptance of field equipment 42002 industrial pipe weldin-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-Ray lighting and quality rating of 2 GB11345-2005 steel fusion welded butt joints, welding engineering-ions, serial number a 1 GB3323icatn team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specif1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and constructio-0strative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 50100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the admini2
1、展示各种情况
首先请同学们在小组内交流一下自己的作品,然后将部分同学的作品贴到黑板上,学生会出现如下情况。
2、进行分类:
(1)相交与否。师:同学们的想象力真丰富,你们所想象的两条直线画下来会有这么多种情况,能给他们分分类吗,先在小组内交流,讨论。
汇报:学生可能出现以下几种情况。第一种,分为两类:交叉的一类,不交叉的一类。第二种,分为三类:交叉的一类,快要交叉的一类,不交叉一类。第三种,分为四类:交叉的一类,快要交叉的一类,不交叉一类,交叉成直角的一类。
师:你们所说的交叉是两条线碰到一块了,在数学上称为相交。
(2) 引导学生分类
在同一平面内两条直线的位置关系:分为相交和不相交两类。这里学生可能对两幅图有疑问:
这时教师引导学生自己发现问题,通过想象直线是可以无限延伸的,同时请两名学生动手画一画,把两幅图中的直线分别延长。学生通过观察与想象很快明确了快要相交的一类也属于两条直线相交的情况,刚才在分类时有的同学把已经相交和快要相交看作不同的两类,因此分成了三类,那分成四类的同学把交叉成直角的看成单独的一类了,其实这也是相交。这样同学们在交流中达成分类共识:即相交的一类,不相交的一类。
100 economic sanctions against them. (4) to conceal the accident, reported without undue de-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-y. (3) personal injury accident occurs, the direct punishment 500ing administrative sanctions should be dealt with by the personnel Department of the compan10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concern-ent occurred, the direct punishment 0.5accid such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injuryrectly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, ies disions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalitned 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provieasures have been taken, the responsible unit fisun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective m2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-lity rating of 2 GB11345Ray lighting and qua-2005 steel fusion welded butt joints, welding engineering-andards and specifications, serial number a 1 GB3323nt and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction st1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accide-dership, along with 500lay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of lea3
(设计意图:在积极探究过程中发展了学生的空间想象能力,在学生自主探究、交流、辨析、求证过程中顺其自然的发现两条直线的两种位置关系。)
(三)自主探究,构建新知
1、认识平行:
师:这组直线会相交吗,你是怎么想的,有的学生认为它不会相交,有的学生觉得两条直线是一样宽的,有的学生则认为是不是一样宽,必须动手量,通过用尺测量,说明两条直线永远不会相交,这种情况在数学上叫互相平行。(课件演示:两条直线向两边无限延伸,进一步说明两条直线向两边无论怎样延伸都不可能相交。)在此基础上揭示概念:在同一平面内,不相交的两条直线叫做平行线,也可以说这两条直线互相平行。
质疑:同一平面是什么意思,教师出示图帮助学生理解,问:平行吗,平行。接着问:这样还平行吗,为什么,因为不在同一平面。 练习:出示下列几组直线,判断哪几组互相平行
在学生讨论的基础上强调:判断两条直线是否平行时“在同一平面内”“不相交”这两个条件缺一不可。
(设计意图:通过学生自学、质疑、解惑这样一个过程,充分发挥学生的学习主动性,促使他们的想象,情感等参与到学习中去,亲身体验,加深理解平行中同一平面,不相交的概念。)
2、认识垂线
师:我们再来看一看两条直线相交的情况,你们发现了什么,学
-criticism and 50 1000, who is directly responsible for the accident responsibility, give notice of-injury accident occurs, the direct punishment 500p, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal 10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadershi-e direct punishment 0.5inistrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, thg adm~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerninfined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1 b unitnstruction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the jon. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, cosun exposure measures, responsibilities of team a fine of 50 Yuag engineering code for construction and acceptance of field equipment 42002 industrial pipe weldin-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-Ray lighting and quality rating of 2 GB11345-2005 steel fusion welded butt joints, welding engineering-ions, serial number a 1 GB3323icatn team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specif1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and constructio-0strative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 50100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the admini4
生可能会回答两条直线相交后都有四个角,我发现这四个角都是直角,我发现对着的两个角一样大。教师追问:你是怎么知道他们相交后形成四个直角呢,学生说:“可以量一量。”(请一学生验证。) 教师小结:如果两条直线相交成直角,我们就说这两条直线互相垂直,其中一条直线叫做另一条直线的垂线,这两条直线的交点叫垂足。 (设计意图:学生从相交后形成的角度来看,发现+,从而引导学生用工具验证相交后成直角的现象,清晰揭示出互相垂直的概念同时注意培养学生科学严谨的学习态度和研究问题的方法。)
3、揭示课题:这就是我们今天学习的
内容
财务内部控制制度的内容财务内部控制制度的内容人员招聘与配置的内容项目成本控制的内容消防安全演练内容
《垂直与平行》
(四)巩固新知,应用提高
1、找一找
a、 出示主题图,找垂直与平行的现象,学生们自主发言。
b、在几何图形中找垂直与平行的现象
2、说一说
在日常生活中有没有垂直与平行的现象,举例说明
平行的例子:五线谱中的五条线,黑板相对的两条边。
垂直的例子:长方形镜框长边和短边互相垂直。
(设计意图:通过一组判断题的练习,让学生进一步理解平行与垂直的概念问题,巩固所学知识,提高学习能力,增强学习信心。) (五)全课
总结
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,评价体验
同学们,这节课你表现怎样,你有什么收获,
dership, along with 500lay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of lea100 economic sanctions against them. (4) to conceal the accident, reported without undue de-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-y. (3) personal injury accident occurs, the direct punishment 500ing administrative sanctions should be dealt with by the personnel Department of the compan10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concern-ent occurred, the direct punishment 0.5accid such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injuryrectly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, ies disions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalitned 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provieasures have been taken, the responsible unit fisun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective m2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-lity rating of 2 GB11345Ray lighting and qua-2005 steel fusion welded butt joints, welding engineering-andards and specifications, serial number a 1 GB3323nt and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction st1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accide-5
垂直与平行一课的教学,以学生知识经验和生活经验为基础,充分调动学生的各种感官,创设情境,联系生活,为学生搭建探究、发现的学习平台,引导学生学会在“做”中学数学,在探究中学数学,在合作交流中学数学,这样真正促进了学生的主动学习,进而获得主动发展。
1000, who is directly responsible for the accident responsibility, give notice of-injury accident occurs, the direct punishment 500p, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal 10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadershi-e direct punishment 0.5inistrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, thg adm~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerninfined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1 b unitnstruction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the jon. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, cosun exposure measures, responsibilities of team a fine of 50 Yuag engineering code for construction and acceptance of field equipment 42002 industrial pipe weldin-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-Ray lighting and quality rating of 2 GB11345-2005 steel fusion welded butt joints, welding engineering-ions, serial number a 1 GB3323icatn team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specif1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and constructio-0strative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 50100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the admini-criticism and 50 6
四年级数学上册
《垂直与平行》教学设计
六枝特区第一小学 郝云桂
教学目标:
1、知识目标:帮助学生初步理解垂直与平行是同一平面内两条直线的两种位置关系,初步认识垂线和平行线。
2、技能目标是:培养学生的空间观念及想象能力。
3、情感目标是:培养学生对生活的感情和合作探究的学习意识。
教学重难点:
教学重点是:正确理解“相交”“互相平行”“互相垂直”等概念,特别要注意对看似不相交,而实际上可以相交现象的理解。
教学难点是:正确理解“在同一平面内”“永不相交”等概念的本质属性。
教具、学具准备:
课件、尺子、三角板、量角器、小棒、白纸、磁铁
教学过程:
一、设置情景,想象感知
师:晚上,吃过晚饭小明在收拾碗筷时,不小心把两根筷子掉在地上了,如果用两根筷子表示两条直线。请同学们发挥想象力猜测一下:两根筷子落在地上可能会形成怎样的图形,请同学们动手画一画。
现在老师和同学们一样都有这样一张纸,大家拿出来摸一摸这张
100 economic sanctions against them. (4) to conceal the accident, reported without undue de-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-y. (3) personal injury accident occurs, the direct punishment 500ing administrative sanctions should be dealt with by the personnel Department of the compan10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concern-ent occurred, the direct punishment 0.5accid such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injuryrectly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, ies disions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalitned 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provieasures have been taken, the responsible unit fisun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective m2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-lity rating of 2 GB11345Ray lighting and qua-2005 steel fusion welded butt joints, welding engineering-andards and specifications, serial number a 1 GB3323nt and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction st1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accide-dership, along with 500lay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of lea7
纸的这个面。有什么感觉,(学生活动)
师:好现在就这张纸的这个平面,我们一起来做个小小的想象活动,想象一下把这个面变大会是什么样子,
师:请同学们闭上眼睛,我们一起来想象。(声音缓慢)这个面变大了,又变大了,变的无限大,这时在这个无限大的平面上,出现了一条直线,又出现一条直线。现在请你们再想象一下这两条直线会形成什么图形,好了,现在睁开眼睛把你刚才想到的图形画在纸的这的这个平面上。注意,一张白纸上只画一种情况。开始吧。(学生试画,教师巡视)
二、探索比较,掌握特征
(一)动手操作,建立表象
1、画图,独立思考,把可能出现的图形画在白纸上。并在小组内进行交流。教师巡视。
2、展示典型图形,强化图形表征。
(1)展示学生的画法(用水彩笔画在白纸上)
(2)除了刚才同学们展示的这几种情况,其他同学还有补充吗,师补充生没有出现的情况
(二)小组合作,感知特征
1、归纳展示,把刚才几个同学所展示的画法进行归纳。粘贴学生的作品。
2、师:同学们的想象力可真丰富,画出来这么多种情况。我们来先把他们标上序号,再把它们按照”相交””不相交”的标准进行
-criticism and 50 1000, who is directly responsible for the accident responsibility, give notice of-injury accident occurs, the direct punishment 500p, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal 10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadershi-e direct punishment 0.5inistrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, thg adm~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerninfined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1 b unitnstruction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the jon. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, cosun exposure measures, responsibilities of team a fine of 50 Yuag engineering code for construction and acceptance of field equipment 42002 industrial pipe weldin-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-Ray lighting and quality rating of 2 GB11345-2005 steel fusion welded butt joints, welding engineering-ions, serial number a 1 GB3323icatn team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specif1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and constructio-0strative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 50100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the admini8
分类,先自己分,分完后在小组中交流交流。(小组讨论、交流)
3、展示各种可能分类方法
4、质疑
对于各小组的分类分法,有什么想法,引导学生侧重按照“相交”和“不相交”的标准进行分类。
三、自主探究,构建新知
导语:通过探索研究,我们发现了在同一平面内,两条直线的位置关系有两种不同情况:一种是相交,一种是不相交。
1、认识“平行”
(1)自学。像这样在同一平面上两条不相交的直线叫什么,课本上是怎么描述的?(课件出示概念)学生齐读概念.
提问:我们把这样的两条直线叫做平行线。那么能不能说直线a或者直线b是平行线呢,为什么,那么你能说一说,谁是谁的平行线吗,还可以怎么说,(教师给两条直线写上字母:a和b) 指名说一说,再同桌互相说一说。
(2)自主探究,认识“在同一平面内”。
谈话:通过刚才的学习,我们知道了两条不相交的直线叫做平行线。现在我们一起来看一下这个粉笔盒,请你们找一下,这个粉笔盒上有哪些平行线,现在我们把a和b是什么关系,a和d是什么关系,
提问:那a和e又是什么关系呢,
学生在这里会出现不同的意见:有的学生会认为它们相交,有的
-andards and specifications, serial number a 1 GB3323nt and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction st1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accide-dership, along with 500lay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of lea100 economic sanctions against them. (4) to conceal the accident, reported without undue de-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-y. (3) personal injury accident occurs, the direct punishment 500ing administrative sanctions should be dealt with by the personnel Department of the compan10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concern-ent occurred, the direct punishment 0.5accid such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injuryrectly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, ies disions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalitned 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provieasures have been taken, the responsible unit fisun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective m2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-lity rating of 2 GB11345Ray lighting and qua-2005 steel fusion welded butt joints, welding engineering9
学生会认为它们平行,有的学生感觉到它们既不相交,又不平行,但不知道原因,等等。
谈话:刚才,同学们通过观察,发现这两条直线有点奇怪,不相交,但是也不平行,那这是什么原因呢,同学们以小组为单位,拿出课前准备的长方体模型,仔细观察,互相讨论,想想这是为什么呢, 组织学生先观察讨论,再进行交流,引导学生认识到a和e在不同平面上,所以它们既不相交,也不平行。
小结:我们今天研究的都是在同一平面内的两条直线。在同一平面内,两条直线不相交就一定平行,也就是说,在“同一平面内”(教师用彩色粉笔板书)不相交的两条直线互相平行。关于这个问题,我们以后到中学还要继续研究。下面我们一起把这句话一起读一读。
3、联系生活,找出实例。
平行线在我们的生活中有着广泛的应用,现在我们来找找看,在我们周围都有那些平行线,很好,原来生活中有这么多平行线存在。现在再来看看这幅图:熟悉吗,你能从这些图中相互平行的例子吗, 先让学生自己说说,再全班交流。在交流过程中,注意及时评价,并捕捉有效的资源。
例如:学生说到斑马线的平行线时,提问:谁能具体说一说,在斑马线中,哪条直线和哪条直线互相平行啊,(学生说说)
追问:奇怪了,刚才有同学说这一条直线和那条直线平行,但又有同学说是和另外一条直线平行的,那到底谁对呢,那你们想一组平行线可以有几条呢,(可以是两条,也可以是三条、四条、五条等。)
criticism and 50 1000, who is directly responsible for the accident responsibility, give notice of-injury accident occurs, the direct punishment 500p, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal 10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadershi-e direct punishment 0.5inistrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, thg adm~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerninfined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1 b unitnstruction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the jon. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, cosun exposure measures, responsibilities of team a fine of 50 Yuag engineering code for construction and acceptance of field equipment 42002 industrial pipe weldin-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-Ray lighting and quality rating of 2 GB11345-2005 steel fusion welded butt joints, welding engineering-ions, serial number a 1 GB3323icatn team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specif1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and constructio-0strative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 50100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the admini-10
再问:单单一条直线行不行,(不行)
小结:对,平行指的是同一平面内直线之间的位置关系,如果只有一条,就谈不上位置关系了。因此,一组平行线至少要有两条。
2、认识“垂直”
1、通过上面的学习,我们知道了同一平面内不相交的两条直线叫做平行线。现在请同学们再仔细观察左边这些作品,它们都是相交的,相交后都形成了什么,
2、师:对了相交后都成了四个角,现在请你们观察一下这些角,看看有什么发现,
3、那这些真是直角吗,谁能用三角尺验证一下,是不是直角,师:你们很厉害,都被你们说中了,他们相交成了直角。数学上把这种相交成直角的两条直线称为什么。
4、师:大家都说的不错,我们一起来看大屏幕,当两条直线相交成直角时,我们就说这两条直线互相垂直。这两条直线叫做垂线(课件出示)我们一起来读一读。
5、师:如果,我们把一条直线看作直线a,另一条直线看作直线b,谁来说一说谁是谁的垂线,谁与谁互相垂直,
6、(课件:闪一闪)我们也可以说直线a是直线b的垂线,直线b是直线a的垂线,直线a和直线b互相垂直。
7、教学垂足的概念。这两条直线的交点叫做垂足。(课件:箭头指示一次)
8、师:当两条直线相交成直角时(板书:成直角)我们说这两
1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accide-dership, along with 500lay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of lea100 economic sanctions against them. (4) to conceal the accident, reported without undue de-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-y. (3) personal injury accident occurs, the direct punishment 500ing administrative sanctions should be dealt with by the personnel Department of the compan10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concern-ent occurred, the direct punishment 0.5accid such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injuryrectly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, ies disions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalitned 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provieasures have been taken, the responsible unit fisun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective m2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-lity rating of 2 GB11345Ray lighting and qua-2005 steel fusion welded butt joints, welding engineering-andards and specifications, serial number a 1 GB3323nt and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction st11
条直线互相垂直(板书),(与一般的相交作一个比较)而这几组直线相交没有形成直角,是一般的相交,所以它们不是互相垂直。
9、生活中有没有互相垂直的现象,说一说、指一指,(课件出示)在这些图片中你能找到垂线吗,(我们的身边互相垂直的现象还有很多很多。)
(四)、巩固练习,形成技能
1、通过上面的学习,我们知道了什么是平行和垂直,现在我们来看看这几幅图形,请你们来说一说这些图形中互相平行和垂直的线段。
2、很好,同学们表现得都十分出色。那这幅图你们熟悉吗,一起来找找看这里有哪些平行和垂直的例子。
3、还想再挑战一下自己吗,我们来看下这两条鱼,这是两条一模一样的鱼,那你们能不能从这条鱼身上找到互相平行的线段。看谁的眼睛最亮,找到得最多。
(五)、课堂小结,学会评价
通过这节课的学习,你们学到了什么,你觉得自己表现怎么样,其他同学呢,
(六)作业布置:完成第65页的做一做和第68页的第三道题。
-criticism and 50 1000, who is directly responsible for the accident responsibility, give notice of-injury accident occurs, the direct punishment 500p, such as concerning administrative sanctions should be dealt with by the personnel Department of the company. (3) personal 10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadershi-e direct punishment 0.5inistrative sanctions, should be brought to the company or the relevant Department. (2) personal injury accident occurred, thg adm~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, such as concerninfined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalities directly punished 1 b unitnstruction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provisions, on the jon. (7) at height and the opening and provisional protective measures have been taken, the responsible unit fined 200 Yuan, cosun exposure measures, responsibilities of team a fine of 50 Yuag engineering code for construction and acceptance of field equipment 42002 industrial pipe weldin-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-Ray lighting and quality rating of 2 GB11345-2005 steel fusion welded butt joints, welding engineering-ions, serial number a 1 GB3323icatn team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction standards and specif1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accident and constructio-0strative leadership of the criticism, resulting in serious consequences, the pursuit of leadership, along with 50100 economic sanctions against them. (4) to conceal the accident, reported without undue delay or false, to inform the admini12
(七)板书设计
平行与垂直
lay or false, to inform the administrative leadership of the criticism, resulting in serious consequences, the pursuit of lea100 economic sanctions against them. (4) to conceal the accident, reported without undue de-1000, who is directly responsible for the accident responsibility, give notice of criticism and 50-y. (3) personal injury accident occurs, the direct punishment 500ing administrative sanctions should be dealt with by the personnel Department of the compan10,000 yuan, responsible for the direct responsibility for the accident and the responsibility of leadership, such as concern-ent occurred, the direct punishment 0.5accid such as concerning administrative sanctions, should be brought to the company or the relevant Department. (2) personal injuryrectly punished 1~2 million. Direct responsibility for the accident and have the corresponding responsibility of leadership, ies disions, on the job unit fined 300 yuan, the unit will charge a fine of 100 Yuan. 7.5.3 accident penalties (1) injuries fatalitned 200 Yuan, construction person in charge a fine of 50 Yuan. (8) no permit to work and the job in accordance with the provieasures have been taken, the responsible unit fisun exposure measures, responsibilities of team a fine of 50 Yuan. (7) at height and the opening and provisional protective m2002 industrial pipe welding engineering code for construction and acceptance of field equipment 4-89 steel welds manual methods of ultrasonic inspection and testing results for grade 3 GB50236-lity rating of 2 GB11345Ray lighting and qua-2005 steel fusion welded butt joints, welding engineering-andards and specifications, serial number a 1 GB3323nt and construction team injuries accident penalty provisions, mutatis mutandis. Eight, should perform in the construction st1000 punishment. (5) significant near miss should be attempted as the case of responsible for the accide-dership, along with 50013