维生素C的故事

维生素C的故事 18、维生素C的故事 一、教材分析: 这是一篇介绍维生素C作用的科普小品。文章采用故事的形 式，借助于曲折的情节，生动地向读者介绍了维生素C的有关知 识。 二、教学目标 1、学会本课的10个生字。正确、流利有感情的朗读课文，初步 掌握课文的。 2、熟读课文，了解维生素C的发现过程，懂得任何创造都离不 开细心地观察与实践。 3、在朗读中感受体验哥伦布情感的变化，明白其变化的原因;能 运用文中的语言或自己的语言复述故事。 三、教学重难点 教学重点: 1、了解维生素C被人们发现的过程。 2、感受哥伦布心情的变化，明白其变化的原因。 教学难点: 1、了解维生素C的发现过程，懂得任何、创造都离不开细心地 观察与实践。 2、能运用文中的语言或自己的语言复述故事。 三、教学评价设计 1、在整体感知环节，借助预习单，了解学生尤其是学困生识、 写生字以及正确、流利读书的情况。 2、在精读感悟环节主要采取读中感悟来达到人物心情的目 标。在这一环节，引导学生找中心句，找关键词来把握课文的主poverty. In the area of poverty alleviation, to rely on e-commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to accelerate the implementation of electronic commerce "hundred thousand rural village" project, free train operation staff, offering online support help for poor families, the provision of micro-credit support, helping them to use e-commerce platform to escape poverty. In poverty reduction, give a man a fish and feed him for a day, to targeted skills training and entrepreneurship training free of charge for the poor, increase employment, entrepreneurial skills, ensure the transfer of training people, poverty. In terms of student poverty, high school, vocational college students ' stipends and other costs, can be through the "one card", such as direct subsidies to households. In terms of financial poverty, in order to further increase the size of loans, expands the scope of delivery, developing industry, Enterprise provides protection for the poor. In respect of transport poverty alleviation, to solve the bottleneck in poor villages, development of transport, vigorously promoting the construction of rural roads and ordinary roads. PV poverty reduction, to support conditions of poor villages and photovoltaic system of centralized, poor construction projects, poor 要内容。通过多种形式的读书、圈画、注释、交流等形式自读自悟，培养了学生的自学能力。 3、通过拓展作业，扩大学生的知识面，激发学生对科学的热爱。 4、整个学习的过程中，关注学生的情感体验，关注学生的自主学习、合作学习，并及时作出评价。 四、教学准备: 1、学生:认真读课文，完成预习单。 2、教师:查看学生预习单。 课件 五、教学时间:2课时 六、教学设计 第一课时 环节一、整体感知------初读感知，整体把握 (一)、板书课题，导入新课 1、齐读课题，质疑课题。 读了课题，你想提出哪些问题,(质疑课题，培养学生动脑的习惯，激发学生从文中寻找答案的欲望。在这一环节，教师可以根据学生提出的问题，有共性的、重点的作为学习的目标，如:维生素C是什么东西,它有什么作用,它是怎么被发现的,谁发现的,等。而其他一些简单的能立刻做出回答的则及时回答。) 2、同学们真会提问题。爱动脑筋、爱思考是个很好的学习习惯，好多的发明、创作就是在这些不经意的提问、思考，进一步探索研究后得到的。 (二)、检查预习 expands the scope of delivery, developing industry, Enterprise provides protection for the poor. In respect of transport pove card", such as direct subsidies to households. In terms of financial poverty, in order to further increase the size of loans, "one poverty. In terms of student poverty, high school, vocational college students ' stipends and other costs, can be through the ip training free of charge for the poor, increase employment, entrepreneurial skills, ensure the transfer of training people,ing and entrepreneurshcommerce platform to escape poverty. In poverty reduction, give a man a fish and feed him for a day, to targeted skills train-credit support, helping them to use e-offering online support help for poor families, the provision of microaccelerate the implementation of electronic commerce "hundred thousand rural village" project, free train operation staff, commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -ly on epoverty. In the area of poverty alleviation, to re2oor construction projects, poorzed, pal roads and ordinary roads. PV poverty reduction, to support conditions of poor villages and photovoltaic system of centralialleviation, to solve the bottleneck in poor villages, development of transport, vigorously promoting the construction of rurrty (出示预习单:) 1、检查生字，指名读，说说你是怎么识记这些生字的。(针对学生的识记情况及时作出评价。其中，重点指导“乏、适”的写法，捺要长一些。) 2、积累词语。 路程 缺乏 艰苦 浑身无力 物资 适量 危险 又惊又喜 指名读， 齐读。 (三)、初读课文，整体感知 1、指名分段读课文，读通、读顺。 想一想每一段都讲了什么, 2、交流初读理解。 通过读课文，课前提出的问题你解决了哪些,(学生大体交流自己的读书收获，不必做细致的分析。) 交流哥伦布的有关资料，齐读第一自然段。 3、默读课文，说说课文主要讲了什么事情,(在多读课文、了解每一部分内容的基础上引导学生概括课文的主要内容，初步整体感知课文。) 环节二、部分理解-----精读感悟，重点突破。 (四)、品读课文，理解航海生活的“艰苦、危险” 1、课文时围绕着哪句话写的, (那时、航海生活不光十分艰苦，而且充满危险。------引导学生 明白这是对航海生活总的感受和评价，全文也是围绕着这句话 来写的。) 3y reduction, to support conditions of poor villages and photovoltaic system of centralized, poor construction projects, poorpovertneck in poor villages, development of transport, vigorously promoting the construction of rural roads and ordinary roads. PV oping industry, Enterprise provides protection for the poor. In respect of transport poverty alleviation, to solve the bottledevelto households. In terms of financial poverty, in order to further increase the size of loans, expands the scope of delivery, high school, vocational college students ' stipends and other costs, can be through the "one card", such as direct subsidies verty,he poor, increase employment, entrepreneurial skills, ensure the transfer of training people, poverty. In terms of student poion, give a man a fish and feed him for a day, to targeted skills training and entrepreneurship training free of charge for tcommerce platform to escape poverty. In poverty reduct-credit support, helping them to use e-poor families, the provision of micro of electronic commerce "hundred thousand rural village" project, free train operation staff, offering online support help foraccelerate the implementation commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -poverty. In the area of poverty alleviation, to rely on e 这句话中关键词是什么,(艰苦、危险)齐读这句话。 2、小组合作探究 先用笔在文中画出有关语句，并在旁边作注释。 小组内讨论:哪些句子写出了航海生活的艰苦,哪些句子写出 了航海生活的危险,说出你的理解。 3、交流并读书推进读懂: (1)体会“艰苦” 出示:船员们在船上只能吃到黑面包河咸鱼。 “只能”是什么意思,说明什么,指导朗读，要重读“只 (引导学生理解船员们食品的单一，为下一步理解得“怪病” 的原因及治疗的作下铺垫。) 同学们想一想除了食物的单一，可能还有什么艰苦,(鼓励学 生展开想象，进一步体会航海生活的艰苦。) (2)体会“危险” 出示:最可怕的是在航海期间很容易得一种怪病，病人先是感到浑身无力，走不动路，接着就会全身出血，然后慢慢地死去。船员们都把 “海上凶神”。 这种怪病叫做 “海上凶神”是一种什么样的病,得了这种病会怎么样, “最可怕”说明了什么, “先???接着???然后???”写出了这种怪病的发生和发展过程。练习用 “先???接着???然后???”写一句话，来表现事情的先后顺序。 指导朗读，读出“海上凶神”的可怕。(通过理解“海上凶神”的可 怕体会航海生活的危险。) 齐读这句话。 老师总结并过渡:哥伦布带领的船队在大西洋上乘风破浪，远航探险。 生活非常艰苦，只能吃到黑面包和咸鱼;而且很容易得“海上凶神” "one poverty. In terms of student poverty, high school, vocational college students ' stipends and other costs, can be through the ip training free of charge for the poor, increase employment, entrepreneurial skills, ensure the transfer of training people,ing and entrepreneurshcommerce platform to escape poverty. In poverty reduction, give a man a fish and feed him for a day, to targeted skills train-credit support, helping them to use e-offering online support help for poor families, the provision of microaccelerate the implementation of electronic commerce "hundred thousand rural village" project, free train operation staff, commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -ly on epoverty. In the area of poverty alleviation, to re4oor construction projects, poorzed, pal roads and ordinary roads. PV poverty reduction, to support conditions of poor villages and photovoltaic system of centralialleviation, to solve the bottleneck in poor villages, development of transport, vigorously promoting the construction of rurrty expands the scope of delivery, developing industry, Enterprise provides protection for the poor. In respect of transport pove card", such as direct subsidies to households. In terms of financial poverty, in order to further increase the size of loans, 的怪病。那么这种怪病和课题中的“维生素C”有什么关系呢，让我们 走近哥伦布，跟随他一起去经历一次危险而又难忘的奇迹之旅。(这 些导语，意在激发学生的阅读期待，以达到“未成曲调先有情”的效果， 为下面的学习奠定好基。 (五)精读课文3---6小结，体会哥伦布心情的变化。 1、同学们自读课文3-6自然段，边读边画出描写哥伦布心情变化的 有关词句。用“先???然后???最后???”说说哥伦布心情的变化。 2、精读每一小节，小组内说说哥伦布心情变化的原因。 出示课件:哥伦布的心情先是( )因为( );接着他的眼里噙着泪 );然后( )是因为( );最后( )那是因为( )。 水因为( (教师可以利用这些填空帮助学生理清哥伦布心情变化的过程以及变化的原因。) 3、交流引导，并指导朗读。 (1)出示:望着四周一片茫茫的海水，哥伦布的心情十分沉重。 为什么“心情十分沉重”,(联系第二自然段得这种怪病的可怕，来理解哥伦布在遇到这种怪病时的忧心忡忡、茫然无助的复杂心情。) 指导朗读第3小结。 (2)是什么原因让哥伦布眼里噙着泪水呢,假如你是哥伦布，此时你会怎么想,(联系上文展开想象，体会哥伦布心中对这些得病船员主动要求留在荒岛的感动和无可奈何。) (3)几个月过去了，哥伦布的船队胜利返航了，为什么他的心情却越来越沉重了呢, (引导学生理解这次探险成功得来的不容易，是用十几个船员的生命换来的，体会哥伦布伤心欲绝。) 练习用“越来越???越来越???”写话。 指导感情朗读，感受哥伦布的悲痛欲绝的心情。 verty,he poor, increase employment, entrepreneurial skills, ensure the transfer of training people, poverty. In terms of student poion, give a man a fish and feed him for a day, to targeted skills training and entrepreneurship training free of charge for tcommerce platform to escape poverty. In poverty reduct-credit support, helping them to use e-poor families, the provision of micro of electronic commerce "hundred thousand rural village" project, free train operation staff, offering online support help foraccelerate the implementation commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -poverty. In the area of poverty alleviation, to rely on e5y reduction, to support conditions of poor villages and photovoltaic system of centralized, poor construction projects, poorpovertneck in poor villages, development of transport, vigorously promoting the construction of rural roads and ordinary roads. PV oping industry, Enterprise provides protection for the poor. In respect of transport poverty alleviation, to solve the bottledevelto households. In terms of financial poverty, in order to further increase the size of loans, expands the scope of delivery, high school, vocational college students ' stipends and other costs, can be through the "one card", such as direct subsidies (4)体会“又惊又喜” 是什么让“悲痛欲绝”的哥伦布变得又惊又喜的, 指导分角色朗读感受哥伦布的惊讶万分、欣喜若狂的激动心情。 (六)品读维生素C的发现 如果你听了那些得了怪病的船员的话你会想什么,哥伦布是 怎么想的,怎么做的, 1、默读7、8自然段。 从中你了解了什么, 2、简单交流维生素C的有关资料。 3、指名读这两小结，揭示维生素C的发现。 “一???就???” 说明什么, 谈谈此时你对哥伦布又有了什么样的认识, (在这一环节主要是以读为主，读远航结束时哥伦布的想法和做法，来体会哥伦布急于揭开秘密的迫切心情，并从中懂得在生活中碰到奇怪的事情要善于思考，多问几个为什么，提出有价值的问题，问题往往是新发现的开始。) 环节三、回归整体-----积累拓展，读写训练 (七)总结全文，揭示主题 1、小结:哥伦布得知那些留在荒岛上的船员活下来的原因后，并没有停止探究，而是急切地把他的疑问告诉了医生，最后才发现了维生素C。这就说明了许多科学的新发现都是在生活实践中经过细心观察、反复研究才获得的。 2、探索哥伦布的航海和维生素C有什么关系。(引导学生明白是哥伦布在航海的过程中发现野果子中有可以抗“海上凶神”的维生素C，所以本课看似写航海生活实是写维生素C 6oor construction projects, poorzed, pal roads and ordinary roads. PV poverty reduction, to support conditions of poor villages and photovoltaic system of centralialleviation, to solve the bottleneck in poor villages, development of transport, vigorously promoting the construction of rurrty expands the scope of delivery, developing industry, Enterprise provides protection for the poor. In respect of transport pove card", such as direct subsidies to households. In terms of financial poverty, in order to further increase the size of loans, "one poverty. In terms of student poverty, high school, vocational college students ' stipends and other costs, can be through the ip training free of charge for the poor, increase employment, entrepreneurial skills, ensure the transfer of training people,ing and entrepreneurshcommerce platform to escape poverty. In poverty reduction, give a man a fish and feed him for a day, to targeted skills train-credit support, helping them to use e-offering online support help for poor families, the provision of microaccelerate the implementation of electronic commerce "hundred thousand rural village" project, free train operation staff, commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -ly on epoverty. In the area of poverty alleviation, to re 的发现过程。) (五)课外延伸: 1、这个故事讲给家人听或者用自己的语言或书上的语言把这个故事复述下来。 2、截至目前为止，人们已经发现了维生素A、B、C、D、E„„不下几十种不同的种类，随着科学技术的不断发展，人们的不断研究，今后将会发现更多的维生素。他们所起到的保健作用也是各不相同，课后你们可以和自己的小伙伴一起去查阅资料，利用班队课举办一次有关“维生素家族”的活动，让我们大家共同学习更多的知识，好吗, 板书设计: 18、维生素C的故事 艰苦 黑面包、咸鱼 食品单一 危险 “海上凶神”(坏血病) 缺少维生素C 18、《维生素C的故事》预习单 一、先在课本上描红，然后在下面的田字格里仿写一个。做到正确、。 艰 浑 程 累 尸 秘 质 乏 适 愈 二、正确的读一读，抄一抄，再听写。 路程 缺乏 艰苦 浑身无力 物资 适量 危险 又惊又喜 7y reduction, to support conditions of poor villages and photovoltaic system of centralized, poor construction projects, poorpovertneck in poor villages, development of transport, vigorously promoting the construction of rural roads and ordinary roads. PV oping industry, Enterprise provides protection for the poor. In respect of transport poverty alleviation, to solve the bottledevelto households. In terms of financial poverty, in order to further increase the size of loans, expands the scope of delivery, high school, vocational college students ' stipends and other costs, can be through the "one card", such as direct subsidies verty,he poor, increase employment, entrepreneurial skills, ensure the transfer of training people, poverty. In terms of student poion, give a man a fish and feed him for a day, to targeted skills training and entrepreneurship training free of charge for tcommerce platform to escape poverty. In poverty reduct-credit support, helping them to use e-poor families, the provision of micro of electronic commerce "hundred thousand rural village" project, free train operation staff, offering online support help foraccelerate the implementation commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -poverty. In the area of poverty alleviation, to rely on e 三、朗读课文，了解课文的主要内容。 1、朗读课文，做到读通、读顺、读正确，难读的句子或长句子要多读几遍。 2、熟读课文，初步了解维生素C发现的过程。 四、查阅资料 通过上网或看书了解哥伦布，收集维生素C的有关资料。 "one poverty. In terms of student poverty, high school, vocational college students ' stipends and other costs, can be through the ip training free of charge for the poor, increase employment, entrepreneurial skills, ensure the transfer of training people,ing and entrepreneurshcommerce platform to escape poverty. In poverty reduction, give a man a fish and feed him for a day, to targeted skills train-credit support, helping them to use e-offering online support help for poor families, the provision of microaccelerate the implementation of electronic commerce "hundred thousand rural village" project, free train operation staff, commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -ly on epoverty. In the area of poverty alleviation, to re8oor construction projects, poorzed, pal roads and ordinary roads. PV poverty reduction, to support conditions of poor villages and photovoltaic system of centralialleviation, to solve the bottleneck in poor villages, development of transport, vigorously promoting the construction of rurrty expands the scope of delivery, developing industry, Enterprise provides protection for the poor. In respect of transport pove card", such as direct subsidies to households. In terms of financial poverty, in order to further increase the size of loans, 教学反思: 成功之处 一、抓“海上凶神”关键词，体会航海之苦，探究船员病因。 通过读文，学生很快能从文章的最后一个自然段读懂，所谓的“海上凶神”实际上就是“坏血病”，它是由于人体长期缺乏维生素C引起的。可是，在当时，哥伦布及他的船员知道这是一种什么病吗,(不知道)得了这病有怎样的症状,(病人先是感到浑身无力，走不动路，接着就会全身出血，然后慢慢地死去。)指导学生读好这句话，读出“海上凶神“的可怕。 “那时，航海生活不光非常艰苦，而且充满危险。”这是课文第二自然段的中心句。这句话不仅点明了航海的艰险，更暗含了船员们得病的原因:因为在漫长的航海生活中，船员们所能吃到的只有黑面包和咸鱼。 二、抓哥伦布情感线索，感受人物心理，探究发现过程。 哥伦布的情感变化是串联整个故事的一条比较明显的线索，教学中紧扣这条线索，不仅能突出重点，而且有利于激发学生学生的探究意识使学生更好地把握课文主旨。教学中，引导学生着重体会，哥伦布在航海不到一半路程看到已经有十几个船员相继病倒时“心情十分沉重”。那些病重的船员为了不拖累大家，主动要求留在荒岛，哥伦布“噙着眼泪点了点头„„”的矛盾心情。当哥伦布的船队胜利返航接近荒岛时哥伦布心情“越来越沉重”。到最后看到他的那些船员劫后余生时的“又惊又喜”。进而引导学生以“重逢”为题，想象说话。把那些在荒岛上的船员是如何活下来的，说出来。通过他们前后所吃食物的不同探究治愈“海上凶神”这种怪病的良方，从而揭开它神秘的面纱。哥伦布得知那些留在荒岛上的船员活下来的原因后，并没有停止探究，而是 9y reduction, to support conditions of poor villages and photovoltaic system of centralized, poor construction projects, poorpovertneck in poor villages, development of transport, vigorously promoting the construction of rural roads and ordinary roads. PV oping industry, Enterprise provides protection for the poor. In respect of transport poverty alleviation, to solve the bottledevelto households. In terms of financial poverty, in order to further increase the size of loans, expands the scope of delivery, high school, vocational college students ' stipends and other costs, can be through the "one card", such as direct subsidies verty,he poor, increase employment, entrepreneurial skills, ensure the transfer of training people, poverty. In terms of student poion, give a man a fish and feed him for a day, to targeted skills training and entrepreneurship training free of charge for tcommerce platform to escape poverty. In poverty reduct-credit support, helping them to use e-poor families, the provision of micro of electronic commerce "hundred thousand rural village" project, free train operation staff, offering online support help foraccelerate the implementation commerce business park, active docking Alibaba group "rural treasure", "the stars plan" and "featured the Museum" project to -poverty. In the area of poverty alleviation, to rely on e 急切地把他的疑问告诉了医生，最后才发现了维生素C。这样文章主旨的揭示就水到渠成了:“许多科学的新发现都是在生活实践中经过细心观察、反复研究才获得的。” 不足之处: 1、对于本课的积累拓展方面处理的不够好;读写训练指导较少。 2、由于时间安排的不恰当，所以对于目标3中的复述课文没有能在课上完成。 教学建议: 本文讲述了16世纪意大利伟大的航海家哥伦布在带领船队在大西洋上乘风破浪，远航探险途中，船员们中十几人得了“海上凶神”这种疾病，但是在荒岛上他们却奇迹般地起死回生了。从而发现了维生素C的存在，同时为人类治愈“坏血病”找到了方法。本文的重点应该是两点:了解维生素C被人们发现的过程;感受哥伦布心情的变化，明白其变化的原因。所以教学时教师指导学生通过多读多悟，找中心句，抓关键词，感受哥伦布心情的变化，从而理解维生素C的发现过程。 card", such as direct subsidies to households. In terms of financial poverty, in order to further increase the size of loans, "one poverty. 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PV poverty reduction, to support conditions of poor villages and photovoltaic system of centralialleviation, to solve the bottleneck in poor villages, development of transport, vigorously promoting the construction of rurrty expands the scope of delivery, developing industry, Enterprise provides protection for the poor. In respect of transport pove