五年级上册数学教案 3.1 平行四边形 北京版
文档属性
| 名称 | 五年级上册数学教案 3.1 平行四边形 北京版 |  | |
| 格式 | docx | ||
| 文件大小 | 20.9KB | ||
| 资源类型 | 教案 | ||
| 版本资源 | 北京版 | ||
| 科目 | 数学 | ||
| 更新时间 | 2021-01-28 11:39:34 | ||
图片预览
文档简介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平行四边形的认识
教学内容：北京版义务教育教科书五年级上册第三单元：平行四边形的认识。
一、背景分析
1、教材分析
本节课是北京版小学数学五年级上册第三单元《平行四边形、梯形和三角形》的第一节：平行四边形的第1课时。人教版在三年级上册安排了对平行四边形的初步认识，是在认识长方形、正方形之后，在四年级上册又进一步认识了平行四边形，而平行四边形的面积是安排在了五年级上，这样一个循序渐进的过程。苏教版的认识也是安排在了四下，面积是在五上。北京版把平行四边形的认识、面积、以及梯形的认识、面积、三角形的认识、分类、面积全部安排在五上这一个单元里，学生的认知基础是在一年级初步感知过平行四边形，在三四年级学习了长方形、正方形的认识和面积，学习了垂直与平行的基础上进行教学的。因此，根据教材安排的特点，我的设想是：教师要单元地教，学生更要单元的学。就是让学生整体感知本单元的内容，要知道我要学什么，同时运用学习长正方形的方法，先认识特征，在特征的基础上学习周长和面积，也就是要让学生知道怎么学。也就是整体感知——学什么——怎么学，是这一个单元将要贯穿的思路。
平行四边形的认识，为后面学习平行四边形面积打基础，学好这一部分内容，有利于提高学生动手能力，增强创新意识，进一步发展学生对“空间与图形”的兴趣，对学生理解、掌握、描述现实空间，获得解决实际问题的方法有着重要价值。
教材呈现了五部分内容：平行四边形的特征和定义、长方形、正方形与平行四边形的关系、平行四边形特性及应用、平行四边形的底和高、平行四边形的面积， 这节课我们研究前三个问题。教材的编排始终遵循五年级的认知规律和思维规律，注重在学生实践操作中经历解决问题的整个过程，积累解决问题的经验，注意让学生通过动手操作，在实践过程中逐步促进学生空间观念的发展，在整个教材编排体系中起着非常重要的作用。
2、学情分析
本节课是学生在认识了平行四边形以及垂直与平行的关系及对平行四边形有了初步的认识的基础上学习的。且学生的思维水平正处于形象思维到抽象思维的过渡期，求知欲望强及好奇心极强，好奇心是学生学习的内部动机。因此本节课多采用学生动手、探究，深切体会平行四边形的特征。
《数学课程标准》强调：让学生亲身经历将实物抽象成数学模型，并进行解释与应用的过程，从而使它们真正掌握数学知识与技能，理解数学思想与方法，获得广泛的数学活动经验，为此我确定本节课的教学目标。
二、教学目标
知识与技能： 在图形具体的活动中认识平行四边形，知道它的基本特征；能正确判断平行四边形；掌握平行四边形的特性及在生活中的应用。
过程与方法：学生在观察、操作、比较、判断等活动中，经历探索平行四边形的基本特征的过程，进一步积累认识图形的经验，发展空间观念。
情感态度价值观：学生体会平行四边形在生活中的广泛应用，培养数学应用意识，增强认识平面图形的兴趣。
三、教学重难点
重点：认识平行四边形的特征。
四、教学过程
（一）单元整体感知
1、从这节课开始我们将进入第三单元的学习，出示单元课题：平行四边形、梯形和三角形。看到这个题目，你觉得这个单元要学习哪些内容？
预设：（1）平行四边形、梯形和三角形。
(2) 平行四边形的认识、面积；梯形的认识、面积；三角形的认识、面积。
【设计意图：学生整体感知本单元内容，知道本单元都包括哪些知识，做到不但要单元地教，更要单元地学。】
2、今天这节课我们就先来认识平行四边形。（板书课题：）
（二）认识平行四边形的特征
1、在我们的生活中你们见过平行四边形么？
【设计意图：引导学生在生活情境中发现数学问题，激活学生已有的经验，使学生主动地参与学习过程。】
2、画平行四边形。
看来生活中有很多平行四边形，平行四边形到底什么样呢？你脑中有平行四边形了吗？用手比划比划。
那我们能不能自己画一个平行四边形呢？请同学们在方格纸上画一个平行四边形。（准备方格纸）
（1）学生在方格纸上画平行四边形。教师巡视，了解学生的画图情况，纠正学生的错误操作。
3、研究特征
（1）猜测：
展示，先出示不平行的
这个是平行四边形吗？为什么？
再出示正确的平行四边形，这个是吗？为什么？
预设：对边平行、对边相等、对角相等。
到底是不是如大家所说，平行四边形有这样的特征呢？我们有猜测，还应该进行验证。
（2）验证
要求：1、小组合作，利用三角板、直尺、量角器等学具对平行四边形进行验证。2、把量出的数据记录在你的平行四边形上。
教师巡视、指导学生
（3）汇报交流。预设:
量一量:发现平行四边形两组对边分别相等、对角相等。
移一移：说明平行四边形的两组对边分别平行。
5、抽象概括平行四边形的定义。
现在我们对平行四边形有了一定的认识，那请你说说什么是平行四边形?
【设计意图：本环节的教学比较开放，放手让学生去探究平行四边形的边、角有什么特点。通过问题的引领，给学生充分的动手操作、合作交流的时间和空间，教师适时的给予点拨，以便于学生加以总结和概括。】
6、你能用七巧板中的两块板拼摆成一个平行四边形吗？
还可以怎样摆？3块，4快
小结：看来这些图形之间是可以相互转化的。
（三）与长方形正方形的关系
1、出示长方形和正方形，让学生判断他们是不是平行四边形？为什么？
引出平行四边形和长方形、正方形的关系。（课件演示）
2、课件：你能将图中的三个图形分别割补成学过的长方形吗？
（四）平行四边形易变形的特性
（五）、总结全课：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平行四边形的认识
教学内容：北京版义务教育教科书五年级上册第三单元：平行四边形的认识。
一、背景分析
1、教材分析
本节课是北京版小学数学五年级上册第三单元《平行四边形、梯形和三角形》的第一节：平行四边形的第1课时。人教版在三年级上册安排了对平行四边形的初步认识，是在认识长方形、正方形之后，在四年级上册又进一步认识了平行四边形，而平行四边形的面积是安排在了五年级上，这样一个循序渐进的过程。苏教版的认识也是安排在了四下，面积是在五上。北京版把平行四边形的认识、面积、以及梯形的认识、面积、三角形的认识、分类、面积全部安排在五上这一个单元里，学生的认知基础是在一年级初步感知过平行四边形，在三四年级学习了长方形、正方形的认识和面积，学习了垂直与平行的基础上进行教学的。因此，根据教材安排的特点，我的设想是：教师要单元地教，学生更要单元的学。就是让学生整体感知本单元的内容，要知道我要学什么，同时运用学习长正方形的方法，先认识特征，在特征的基础上学习周长和面积，也就是要让学生知道怎么学。也就是整体感知——学什么——怎么学，是这一个单元将要贯穿的思路。
平行四边形的认识，为后面学习平行四边形面积打基础，学好这一部分内容，有利于提高学生动手能力，增强创新意识，进一步发展学生对“空间与图形”的兴趣，对学生理解、掌握、描述现实空间，获得解决实际问题的方法有着重要价值。
教材呈现了五部分内容：平行四边形的特征和定义、长方形、正方形与平行四边形的关系、平行四边形特性及应用、平行四边形的底和高、平行四边形的面积， 这节课我们研究前三个问题。教材的编排始终遵循五年级的认知规律和思维规律，注重在学生实践操作中经历解决问题的整个过程，积累解决问题的经验，注意让学生通过动手操作，在实践过程中逐步促进学生空间观念的发展，在整个教材编排体系中起着非常重要的作用。
2、学情分析
本节课是学生在认识了平行四边形以及垂直与平行的关系及对平行四边形有了初步的认识的基础上学习的。且学生的思维水平正处于形象思维到抽象思维的过渡期，求知欲望强及好奇心极强，好奇心是学生学习的内部动机。因此本节课多采用学生动手、探究，深切体会平行四边形的特征。
《数学课程标准》强调：让学生亲身经历将实物抽象成数学模型，并进行解释与应用的过程，从而使它们真正掌握数学知识与技能，理解数学思想与方法，获得广泛的数学活动经验，为此我确定本节课的教学目标。
二、教学目标
知识与技能： 在图形具体的活动中认识平行四边形，知道它的基本特征；能正确判断平行四边形；掌握平行四边形的特性及在生活中的应用。
过程与方法：学生在观察、操作、比较、判断等活动中，经历探索平行四边形的基本特征的过程，进一步积累认识图形的经验，发展空间观念。
情感态度价值观：学生体会平行四边形在生活中的广泛应用，培养数学应用意识，增强认识平面图形的兴趣。
三、教学重难点
重点：认识平行四边形的特征。
四、教学过程
（一）单元整体感知
1、从这节课开始我们将进入第三单元的学习，出示单元课题：平行四边形、梯形和三角形。看到这个题目，你觉得这个单元要学习哪些内容？
预设：（1）平行四边形、梯形和三角形。
(2) 平行四边形的认识、面积；梯形的认识、面积；三角形的认识、面积。
【设计意图：学生整体感知本单元内容，知道本单元都包括哪些知识，做到不但要单元地教，更要单元地学。】
2、今天这节课我们就先来认识平行四边形。（板书课题：）
（二）认识平行四边形的特征
1、在我们的生活中你们见过平行四边形么？
【设计意图：引导学生在生活情境中发现数学问题，激活学生已有的经验，使学生主动地参与学习过程。】
2、画平行四边形。
看来生活中有很多平行四边形，平行四边形到底什么样呢？你脑中有平行四边形了吗？用手比划比划。
那我们能不能自己画一个平行四边形呢？请同学们在方格纸上画一个平行四边形。（准备方格纸）
（1）学生在方格纸上画平行四边形。教师巡视，了解学生的画图情况，纠正学生的错误操作。
3、研究特征
（1）猜测：
展示，先出示不平行的
这个是平行四边形吗？为什么？
再出示正确的平行四边形，这个是吗？为什么？
预设：对边平行、对边相等、对角相等。
到底是不是如大家所说，平行四边形有这样的特征呢？我们有猜测，还应该进行验证。
（2）验证
要求：1、小组合作，利用三角板、直尺、量角器等学具对平行四边形进行验证。2、把量出的数据记录在你的平行四边形上。
教师巡视、指导学生
（3）汇报交流。预设:
量一量:发现平行四边形两组对边分别相等、对角相等。
移一移：说明平行四边形的两组对边分别平行。
5、抽象概括平行四边形的定义。
现在我们对平行四边形有了一定的认识，那请你说说什么是平行四边形?
【设计意图：本环节的教学比较开放，放手让学生去探究平行四边形的边、角有什么特点。通过问题的引领，给学生充分的动手操作、合作交流的时间和空间，教师适时的给予点拨，以便于学生加以总结和概括。】
6、你能用七巧板中的两块板拼摆成一个平行四边形吗？
还可以怎样摆？3块，4快
小结：看来这些图形之间是可以相互转化的。
（三）与长方形正方形的关系
1、出示长方形和正方形，让学生判断他们是不是平行四边形？为什么？
引出平行四边形和长方形、正方形的关系。（课件演示）
2、课件：你能将图中的三个图形分别割补成学过的长方形吗？
（四）平行四边形易变形的特性
（五）、总结全课：