ARE系统

关键词：

ARE系统（精选五篇）

ARE系统 篇1

1 Nrf2的基本结构

Nrf2/ECH (NF-E2-related factor2/Chick enerythroid-derived CNC-homology factor) 属于CNC (cap-n-collar) 转录因子家族成员。Nrf2含有6个不同的功能区, 分别被命名为Neh1到Neh6 (Nrf2-ECH homology) [2]。Neh1区中有一个亮氨酸拉链结构b ZIP[leucime zipper (b ZIP) ], b ZIP与小Maf蛋白 (small, Maf proteins, 包括Maf G、Maf K、Maf F) 形成异二聚体是Nrf2识别ARE上DNA基序 (GCTGAGT-CA) 并与之结合、启动目标基因转录的重要前提。Neh2区是Nrf2与胞浆蛋白Keap1结合区, Neh2上的ETGE基序在这一过程中有重要作用, ETGE缺失或突变会解除与Nrf2-Keap1的相互作用[3]。Neh1与Neh2之间为2个激活区Neh4和Neh5。Neh4和Neh5与共激活因子CREB结合蛋白CBP结合会促使CBP协同参与对Nrf2目标基因转录活性的激活[4]。

2 Nrf2-ARE通路的调控机制

Nrf2通路是体内关键内源性氧化还原通路之一。正常情况下, Nrf2与胞浆蛋白伴侣分子Keap1锚定在胞浆内, 使其活性处于相对抑制状态;发生氧化应激时, Keap1可以作为一个氧化还原敏感调节器释放Nrf2, 解离后进入细胞核, 在核内基因启动子区与ARE结合, 启动受ARE调控的NQO1的转录。Nrf2信号可以根据细胞内氧化还原水平的改变而快速启动或关闭, 其介导的保护作用主要通过下调胶质细胞的活化实现, 而小胶质细胞和星形胶质细胞是中枢神经系统中氧自由基 (ROS) 的主要来源[5]。Ⅱ相酶主要包括:血红素加氧酶1 (heme oxygenase-1, HO-1) , 谷胱甘肽-S-转移酶族 (glutathione S-transferases, GSTs) 和NAD (P) H醌氧化还原酶1[NAD (P) H quinoneoxidoreductase1, NQO1]。它们协同构成多效的细胞内抗氧化及解毒防御体系, 清除ROS, 驱除内源性及外源性化学物质引起的细胞毒作用, 维持细胞内的氧化还原电位[6]。Itoh等[7]利用Nrf2基因敲除小鼠, 证实了Nrf2与ARE之间的相互作用, 以及对于下游转录因子表达的影响。Nrf2可诱导抗氧化酶基因, 从而抑制活性氧ROS介导的星形细胞凋亡。

3 Nrf2-ARE通路与中枢系统疾病

自由基氧化应激损伤学说是近年来研究的热点[8]。对阿尔茨海默病 (AD) 、帕金森病 (PD) 、肌萎缩侧索硬化症 (ALS) 等神经退行性疾病特定的遗传和环境因素的研究表明, 自由基增多、脂质过氧化、钙稳态失调、细胞色素C释放是氧化应激增强的主要原因, 最终导致神经元凋亡、死亡。氧化应激的增强可能是这些神经退行性疾病的基础[9]。体内外模型显示, Nrf2-ARE通路能有效阻断由于谷胱甘肽 (GSH) 消耗、脂质过氧化、胞内钙超载、神经兴奋性毒素和线粒体电子传递链断裂而致的神经毒性, 而且还能增加神经元能量和氧化还原电位抑制性神经递质信号和代谢过程[10]。

机体有一套复杂的氧化应激应答系统来应对自由基和有毒物质的损害。当暴露于亲电子试剂或活性氧刺激时, 机体自身能诱导出一系列的保护性蛋白, 以缓解细胞所受的损害[11]。这一协调反应是由保护性蛋白DNA上游调节区的ARE来调控的。DNA芯片检测显示, Nrf2在原代星形胶质细胞和神经元中上调ARE调节的基因, 除了基因调节之外, Nrf2还能够调节星形胶质细胞的还原电位、免疫及炎症反应, 以及培养神经元中的Ca2+稳态、生长因子、信号分子和受体通道[12]。而近年来的研究发现, Nrf2通过与ARE相互作用调节编码抗氧化蛋白, 是迄今为止发现的最为重要的内源性抗氧化应激通路[13]。

3.1 ALS

ALS首先由Jean-Martin Charcot医生描述。显著病理表现为选择性运动神经元死亡, 临床表现为肌肉跳动、反射亢进 (上运动神经元受损) 、无力、肌肉萎缩、瘫痪 (下运动神经元损伤) 等, 最后由于呼吸衰竭而死亡。ALS中5%~10%由于家族遗传引起。家族性ALS (f ALS) 中, Cu/Zn超氧化物歧化酶 (SOD) 突变占20%[14]。ALS可能的机制包括氧化应激、谷氨酸兴奋毒作用、异常蛋白聚集及炎症等。研究表明, 氧化应激与以上多种致病机制有关[15]。Nrf2是近年发现的细胞抵抗内外界氧化和化学等刺激的关键因子, 通过与ARE结合上调抗氧化基因的表达, 对抗氧化应激。应用Ⅱ相酶诱导剂干预ALS体外器官型脊髓培养模型, 可激活Nrf2/ARE通路, 诱导NQO1、HO1等表达上调, 降低氧化应激水平, 对THA诱导的选择性运动神经元损伤具有明显保护作用[16]。

Sarlette等[17]的研究表明, ALS患者运动皮层和脊髓运动神经元内的Nrf2蛋白和m RNA表达均明显下降, 在大鼠ALS模型中也观察到明显的HO1的上升, 但是HO1的保护作用极其有限, 仅在起病阶段有作用。Nrf2/ARE通路激活可通过对抗氧化应激、降低谷氨酸毒性、增强蛋白酶功能及抗炎等, 多靶点发挥神经元保护作用。SOD1/G93A转基因小鼠星形胶质细胞选择性过表达Nrf2可以增加神经元的抗氧化损伤能力, 推迟SOD1/G93A转基因小鼠起病时间, 延长生存期[18]。

3.2 PD

PD是一种中老年人常见的运动障碍性疾病, 又称震颤麻痹, 其病理特征为黑质致密区多巴胺能神经元变性缺失和路易小体形成, 临床主要表现为静止性震颤、肌强直、运动迟缓等症状。PD患者的黑质多巴胺神经元进行性减少, 其病理生理过程包括线粒体复合体Ⅰ活性的降低, 脂质、蛋白及DNA氧化物的增加[19]。

Dietz等[20]对PD患者死后解剖发现, Nrf2主要分布在黑质的神经元细胞核内, 处于激活状态。研究证实, PD病变机制中存在着氧化应激Keap1-Nrf2-ARE信号通路的改变。GSH是细胞内主要的巯基抗氧化剂, PD患者中, Nrf2的靶点GSH和Q10水平均降低, 表明PD中Nrf2应答反应减弱或缺失[21]。而Ramsey等[22]的研究发现, a-synuclein和Nrf2缺失导致的神经炎性反应、神经元衰亡和蛋白质的异常聚集是早期PD患者的病理表现。

3.3 AD

AD是最多见的脑变性疾病, 以进行性脑功能失调为特征表现, 主要表现为记忆、认知、语言和行为障碍以及人格改变等。确诊后, 病人的平均存活时间为8~10年。到目前为止, 还没有有效的治疗措施[23]。AD主要的病理变化为老年斑 (SP) 和神经纤维缠结 (NFT) 及神经元丢失。NFT主要由过磷酸化tau缠结后形成, 与AD脑组织神经元减少直接相关[24]。

Smith等[24]的实验表明氧化损伤发生在AD的早期, 在NFT和SP出现之前就已出现。在AD患者脑内发现了过氧化亚硝酸盐, 进一步证明了氧化应激与AD的病理改变直接相关。Nrf2是细胞调节抗氧化应激反应的重要转录因子, 在调控细胞对抗外来异物和氧化损伤方面起重要作用[25]。在AD患者海马中, Nrf2的表达明显下降。Choudhry等[26]发现在AD转基因大鼠中, Nrf2的表达较正常大鼠减少一半, 同时伴有Aβ的聚集。近年研究发现, 激活Nrf2-ARE通路可以减轻Aβ介导的神经功能障碍以及神经毒性, 而Nrf2能够通过抑制氧化应激减少Aβ聚集来发挥保护作用[27]。

4 小结

ARE系统 篇2

Many readers unanimously agree with Dee’s negative image.However, there are still some critics who have different opinions about Dee.Barbara Christian thought Mama’s action of dumping the quilts into Maggie’s lap is unreasonable.The reason of this she explains as that there are different definitions about the heritage. (Christian 3-19) Susan Farrell gives a re-evaluation to Dee, she says about Dee’s mention of heritage and her way of resisting to the oppression to the social racism, and her way is effective. (Farrell 179-186) Sam Witsitt proposes the respect to the differences.he disagrees with the sharp critics about Dee, and thinks she is not supposed to be oppressed and she should have her voice. (Whitsitt443-459)

The negative criticisms about Dee mainly comes from the following five aspects:number one, Dee’s clothes and hair-style;number two, Dee’s using of Luganda greeting and her boyfriend’s Arabian greeting phrase;number three, Dee’s changing her name“Dee”to“Wangero Leewanika Kemanjo!”;number four, her Muslinized by taking her muslin boyfriend home;number five, the total different view on the quilts.The above five aspects are the main reasons of Mama’s conflicts with Dee.However, Dee should not be criticised by the superficial reasons as many predecessors do.

Dee, experiences poverty, oppression from various sources as the colored people do, she suffers much before she goes into school.During the education, she must be influenced by the black people’s civil rights movement in sixties of twentieth century.It is supposed she tries to resist the oppression through participating in the Civil Rights Movement, then changes her hair style and clothes Which Mama redeems it as humorous strange comparative with wool. (257) Mama lives in the rural south, this makes her lack a broad view of the world’s changing.The blacks with different ways to resist the oppression from the whites’s world.Dee’s clothes and hair style is the way of resisting the society’s standard of the settled style.

Dee’s using of Luganda greeting“Wa-su-zo-Tean-o!”is another way of presenting the change.It is proved that Dee’s using of“Wa-su-zo-Tean-o!”is Luganda greeting which means“good morning!”and her boyfriend’s“Asalamalakim”is Arabian greeting which means“peace be with you!”.The two young black people, through the using of African language instead of English, represents their political consciousness and passion in the civil rights movement period. (Li 106) According to Li Rongqing, this is also related with the Pan-African Conference.He further explains that learning a kind of African language is the goal of Dee’s generation.And this is the way of know their history and may lay foundation of strengthening their race consciousness. (Li 109) Walker deliberately depicts Mama as an old south woman, it is speculated that she was embodied with the old traditional and reserved mind toward the new things, even it is a kind of way to represent one’s selfsearching of self-identity.From the very beginning, the narrator Mama who has the privilege to leave negative impression on Dee to the readers.However, at last, the author gives Dee’s voice of mentioning the“heritage”, and try to convey her new thought to mom, “your heritage...it’s a really a new day for us.But from the way you and Maggie still live you’d never know it” (263) .After her left, Mama and Maggie sit there just“enjoying, until it was time to go in the house and go to bed.”Mom’s stubbornness and backwardness seems disapproval to the author’s underlying intention.

It is accorded that Dee’s searching African culture is a jarring parody. (Zhang 84) However, Dee’s changing her name to“Wangero Leewanika Kemanjo!”is also her way to get rid of her oppressed destiny and express her nation roots.When Mama asks what happens to Dee, she resolutely answers, “she’s dead, I couldn’t bear it any longer, being named after the people who oppress me.”It is known to people, when the black people are sold to the slave owners, they give the slaves new name.Thus It is inherited from years to years.Li Rongqin says, “to the slave, when they are deprived of name, they are deprived of culture.” (Li 93) Actually, Dee’s name changing is just one way of searching her own culture identity to get rid of the oppressed one, is the representation of struggling for her surviving.More, slave’s given name is not the pride of their own but the scar in their heart.So Mom holds the misunderstood prejudice of her new name, rigidly thinks the old name is the honor from grandma.Changing name is not the presentation of Dee’s shallowness and betrayal to her own culture, reversely, it is one of the brave way to resist the oppression and to search their own culture identity.Mom’s unacceptable and the critics’s misreading of Dee should be re-corrected.

Mama’s dissatisfaction about Dee’s Moslem boyfriend is her another prejudice toward Dee.In the old south, the plantations are popular to raise pigs, they stored up a great amount of pork in their warehouse, but they scoff at discarding the pork offals to the slaves. (73) This becomes the inheriting insult to the black people.Dee’s boyfriend declaration of not eating collards pork, (260) Although beig described briefly, proves his resisting to the inheriting insult.More, as it is known to people, the dogma of Moslem Koran demands Hakin-a-barber not eating pork.So it is supposed to be one of their religion belief in his heart.From this point, Mom’s dislike to Dee’s boyfriend is not respect to other’s religion, even she thinks Dee betrays her own religion to take a pagan home, it just proves that mother’s incompatible to other’s religion.Learning to accept new changes is an effective way to survive the outward pressure and an new resisting way.

Mama’s stopping of Dee taking away the quilts is a limax of the conflicts between them in the story.It represents the different attitudes toward the heritage“quilt”between Dee and Mama.Li Rongqing interprets the“quilt”heritage as the complexity of political heritage, artistic heritage and family history heritage.He further concludes that:Maggie only inherits the family history part because she can do the quilts by herself, but the main parts of the black people’s“quilt”heritage should be inherited by Dee, because she evaluates the“quilt”heritage both from the aesthetic value and political angle. (Li 45) When Mama asks Dee, “what would you do with them?”she simply but resolutely answers, “hang them, ” (262) the words may have its resources.The blacks’“quilts”in American are parts of art, and their position are settled in the latter part of twentieth century. (Li 45) This special art craft of the blacks’“quilts”has been accepted as works of art for the unique influence. (Li 46) Thus it is observed clearly that Dee evaluates the“quilts”from the aesthetic view.Being viewed as the political heritage, the“quilts”has intimate relationship with The Black Civil Rights Movement, and this relation strengthens the position of the“quilts”as the heritage of American blacks. (Li 48) Dee’s clothes, hairstyle, earrings, etc, is one of the ways of the representation in The Black Civil Rights Movement.The“quilts”are sold to support the various movements of emancipating the slaves, etc.when the“quilts”are considered as family history heritage, they also can be considered as aesthetic and political heritage.Maggie, nervous and maladjusted, is considered as the successor of the family heritage.She can make some more quilts;the most important is that she cherishes the family relationship in more conservative way.Mama trusts Maggie when she dumps the quilts into her lap.Thus Mama give the right to Maggie to inherit the“quilts”as family heritage.Except the reasons of Maggie’s being the family heritage successor, Mama also mentions that Maggie is going to marry John Thomas, it is supposed that through the marriage, Mama wants to help Maggie become a strong and clearly defined individual.Mama, protective as she is to Maggie, is frank about her shortcomings and problems.This is speculated that Maggie is put in the position of family heritage successor mainly for the reason of Mama’s pity and love to Maggie.There is unfairness emotion between Maggie and Dee.

Every reason of Mama’s dislikes to Dee includes the prejudice.Mama is reserved, backward looking person, and herself is branded with the whites culture as well.Mama lacks a broad view of the world to survey the new world’s changing.The author embodies the three female characters different images vividly to express her own complexity of the new consciousness about the heritage.As we know, Alice takes part in The Civil Rights Movement, but she also knows the divergence in the interior of the black groups;and she embodies Dee the new understanding of the Blacks’heritage.The sub-text of the story do gives the new foundation to Dee’s new interpretation.The narrator Mama has limitation in herself too.Dee, from the above reasons, should be re-evaluated, and this point is worthing further noticing.

参考文献

[1]范小玫.美国短篇小说选读[M].厦门:厦门大学出版社, 2009 (2) :253-263.

[2]Christian B T.Everyday Use by Alice Walker.New Brunswick[M].NJ:Rutgers University Press, 1994:3-19.

[3]Farrell S.Flight vs Flight:A Re-evaluation of Dee in Alice Walker’s Everyday Use[J].Studies in Short Fiction, 1998, 35 (2) :179-186.

[4]Whitsitt S.In Spite of It All:A Reading of Alice Walker’s Ev eryday Use[J].African American Review, 2000, 34 (3) :443-459.

[5]李荣庆.新历史主义批评:<外婆的日用家当>研究[M].杭州:浙江大学出版社, 2011.

ARE系统 篇3

1. 教学内容分析

本节课是人教版《英语》七年级上Unit7 How much are these pants?中的Section A部分。教学内容主要包括认知衣物、谈论价钱及购物。本节内容在整个单元的教学中起着重要作用, 为后面学习对话打下了基础。

2. 教学对象分析

本节课的教学对象是七年级的学生, 他们已经初步掌握了听、说、读、写的基本技能, 并且在日常生活中也具备了一定的购物常识。这个年龄段的学生好奇心强, 喜欢观察、发问, 并且具备了一定的合作意识。这为本节课的顺利开展奠定了比较坚实的基础。

●教学目标

知识与技能目标:学习谈论服装的价格, 学会谈论对服装的喜好和购物时使用的礼貌用语。

过程与方法目标:采用引导、启发、鼓励的方式, 结合个人探究活动与小组合作学习活动。整个教学过程以学生为中心。

情感态度与价值观目标:通过购物对话练习教学生如何感谢他人。

●教学重、难点

重点: (1) 词汇:pant, sock, T-shirt, sweater, shoes; (2) 句型:How much is this T-shirt?It’s seven dollars.How much are your shoes?They are thirty dollars.

难点: (1) 会使用how much引导的问句及相应回答; (2) 学会在英语环境下购物。

●教学过程

1. 导入

服装是人们日常生活中的必需品, 学生对此司空见惯, 因此平铺直叙的导入势必无法激发起学生的学习兴趣。

整合点:利用东师理想初中英语教学平台生成交互式的动画以提高学生的学习兴趣, 利用平台素材中本单元的精彩图片组成展示课件来激发学生的好奇心。图1是利用教学平台生成的课件, 教师可利用此翻板游戏与学生互动。

2. 词汇学习

利用恰当的手段进行词汇教学, 通过恰当的方式让学生学习本节课重点词汇的含义和基本用法。

整合点:传统的教学中词汇教学往往比较枯燥乏味, 因此如何将枯燥乏味的学习变得生动有趣而又能够增强学生的认知是本环节的关键。利用教学平台“构建工具”中的“puzzle words”游戏生成工具生成单词交互式游戏 (如图2) , 激发学生的学习兴趣, 并通过游戏使学生牢记这些重点词汇。

3. 句型练习

本环节的目的是让学生能够熟悉并掌握本课重点句型:How much is…?It’s…, How much are…?They are…的用法。

整合点:利用教学平台, 为学生提供交互式自主探究的环境 (如图3) , 让学生在教师的引导下通过观察自己总结出本课的重点句型。

4. 听力训练

通过听力训练巩固所学的单词和句型, 从而强化了教学重点, 更深层次地解决了教学难点。

整合点:传统教学中的听力训练是单纯的声音文件, 为了更好地达成教学目的, 应该营造多种感官刺激的学习环境, 利用教学平台生成声像结合、图文并茂的听力教学环境, 从而有效提高教学质量和效率 (如图4) 。

5. 拓展学习

经过前面的学习, 学生有了一定的知识积累, 在这里设计一个网上开店的活动, 通过这样的活动, 对学生的知识进行拓展, 让他们模拟真实的购物情景, 锻炼了英语表达能力, 扩大了知识面, 增强了审美观, 并采取了一定的评价措施。

ARE系统 篇4

一、呈现单词, 示范读音

英语是一种拼音文字, 英语单词的读与写是“二合一”的, 因此建立音、形、义之间的联系, 将有助于减轻记单词的负担, 提高学习效率。

直观教学法。直观教学法是通过直观的手段, 如图片、实物、课件、简笔画等呈现单词, 边呈现边示范发音, 将单词的发音和词义结合起来, 让学生直观地听清发音, 感知其义。本单元主要教学four至ten 7个数字, 我直接在PPT上呈现数字, 通过播放声音文件, 让学生听清音, 随后示范朗读, 引导学生观察口形后再模仿跟读;通过抽读、小组读、齐读等形式, 达到正确、熟练地朗读。在此基础上, 将学生的注意力引导到字形, 尝试拼读。边拼读边给单词配上音调, 如:Four, F-O-U-R, four.字母用升调读, 单词用降调读。通过询问学生:What’s this/the next number?/How to spell it?等让学生作出回应。另外, 通过用手指演示数字、书空单词等活动, 充分调动多种感官参与, 使教学更直观形象。

情境教学法。情境教学法是指教师在教授新词时, 设置一定的语用情境, 这样既将学生带入真实情境, 引起他们的学习兴趣, 又能顺利导入新课。如在教学“lovely”时, 我通过呈现上一课时Project 1 My puppy中的puppy图片, 教学“lovely”, 接着创设Puppy show情境, 呈现多幅puppy的可爱图片, 使学生在亲身体验中感知其意, 激发表达的欲望。T:What’s this?S:It’s a puppy.T:Look at the puppy.S:It’s lovely.How lovely/A lovely puppy.在此情境中, “lovely”一词得到了充分的感知和运用。

以旧带新法。以旧带新法就是利用学生学过的词来学习新的单词。常用的以旧带新的方法有:借助反义词、同音词, 利用成对词、对称词、字形相近词等。本节课中, 我借助同音词for与four, 降低认读单词的难度, 通过观察字形, 降低记忆单词的难度;借助形近词, 引导学生在pen与ten之间建立联系, 学生会发现只要把“p”换成“t”就变成了另外一个新单词。我还引导学生观察sit与six, nice与nine之间的异同。看似简单, 但学生会觉得好玩、好记, 有助于学生克服记忆单词的害怕心理。

语音归纳法。学习新单词离不开记忆, 记忆的秘诀就在于建立与记忆对象相关的联系。音、形、义结合有利于建立联系, 形成发音规则知识。在词汇教学时, 我注意将语音的知识渗透其中, 让学生初步掌握部分语音拼读知识。如在教four, five时, 让学生体会字母F的发音, 学生在比较朗读中发现字母F发[f]音, 在教学seven时, 列出一些已学的含有字母S的单词, 如six, sister, sleep等, 让学生通过观察、朗读、体会, 予以辨别。

二、组织活动, 操练巩固

采用活动, 倡导体验参与, 让学生在活动中巩固词汇、运用词汇, 有利于提高词汇教学的有效性和积极性。

游戏法。“游戏是儿童的天性”, 游戏有助于激发学生的学习兴趣, 减轻学习压力与负担。运用游戏教学法巩固单词符合小学生活泼好动的特点。如果说在呈现阶段, 学生的任务是理解词义、模仿发音、观察词形, 那么在巩固阶段, 他们的主要任务则是加强辨别和记忆, 逐步达到“听音知义、见形会读”, 即熟练掌握单词的音、形、义。在本节课中, 我开展了两个游戏巩固数字:游戏一:Magic eyes———当看到数字或单词时, 请同学大声读出来;当看到炸弹时一起说:“BONG”;游戏二:Magic ears———只做口形不出声地拼读单词, 让学生猜教师拼的是什么单词, 以巩固单词的音和形。

儿歌法。歌谣具有简洁、明快、读起来朗朗上口的特点, 能使学生沉浸其中, 自觉或不自觉地说英语, 记忆会更加鲜明持久。在本单元中, 我引入了儿歌“Don’t be late again”来巩固数字:One, two, three, four, come in and close the door.Five, six, seven, eight, it’s time for class, but you’re late.Nine, ten, nine, ten, don’t be late again.另外, 充分利用教材中Sound time和Rhyme time版块, 让学生听音模仿, 变换朗读方式, 借助儿歌的曲调和格式, 自编儿歌, 在不断练习的过程中, 培养语感, 提高能力。

三、词句结合, 交际运用

新的课程标准强调学习过程, 重视语言学习的实践性和应用性, 而数字在生活中也被广泛应用。为此, 我通过呈现电话号码, 如报警电话、火警电话或教师、父母的手机号码、办公室号码等, 让学生尝试朗读, 并找到对应的功能, 通过练习, 既巩固单词又为生活服务。随着对本单元知识的深入学习, 我进一步引导学生关注生活中的数字, 如车牌号、门牌号、QQ号、加减法的认读等。创设生日情境, 数数小组人数、自编对话等, 进一步拓展学习渠道, 引导学生在交际中运用。

ARE系统 篇5

●教材分析:

本单元的3个话题紧紧围绕当今世界环境、科技和文化这三大主题展开。

第一部分是让学生学习如何用英语描述和谈论我们生存的自然环境, 形容词的比较级和最高级的运用是这一部分的重点语法项目。本话题主要通过谈论和描述自然界的风光、动植物及生存资源——森林和水, 引入本单元主要语法项目。如果抓住这个话题, 设计一些丰富的教学活动, 既可以综合练习所学知识, 还能培养学生合作精神及创新思维。

●教学目标:

1.知识目标:掌握形容词比较级和最高级的变化规则及用法。用英语谈论自然界中的动、植物, 让学生初步了解它们之间的关系。

2.能力目标:能使用一些简单的英语语句描述和谈论自然界动物和植物之间的关系。能听懂简单的故事, 理解其中的主要人物和事件, 能在教师的指导下参与角色表演等活动, 能将所学语言组织起来, 写出简短的文章。

3.情感目标:通过对自然界的认识, 培养学生热爱自然、保护环境的美好情感, 同时提高学生的交际能力和与他人合作的能力。

●教学重难点:

1.教学重点:通过谈论自然界中的动植物, 学生能用英语与他人谈论我们生存的自然环境, 而且能熟练运用形容词的比较级和最高级, 能与学生就形容词的级别这个话题交换信息, 使学生具有积极参与课堂上各种英语实践活动的兴趣。

2.教学难点:用所学知识会话, 写出简短的文章。

●教学设计:

S te p1:Re vie w

1.Listen to an English song Old Mac Donald Had A Farm to warm up and lead to the new lesson.

2.After listening, the teacher says, “Do you know the name of the song?Yes, it’s Old Mac Donald Had A Farm.It’s about animals and farms.Can we find farms in the city or in the countryside?Which do you prefer, the countryside or the city?”

(设计说明:通过适时合理的提问, 引发学生的思考, 激发学生的表达欲望, 并通过合理想象来完成表述。)

S te p2:Pre s e ntation

1.Lead to 1a.The teacher shows two pictures, one with beautiful scenery in the countryside and the other with polluted scenery in the city, and then speaks to students, “Today we’ll learn Topic1, Unit4.Look at these two pictures.I think most of us prefer the countryside.It has fresher air, bluer sky, greener trees and clearer rivers.People can enjoy the beauties of nature there.”

Write down the underlined words and let students learn the newones.Master“countryside”, “sky”, “clear”and“nature”.Uderstand the new word“beauty”.Then mark“fresher”, “bluer”, “greener”and“clearer”with colored chalk and let students observe them to get an initial perception of comparative degree of adjectives.

(设计说明:通过两张图片的对比, 引入形容词比较级, 在情境中提高学生的语言交际能力, 凸显语言交际功能。)

2.Listen to 1a, and answer the following questions.

(1) Does Wang Wei like the life in the countryside?

(2) Howdoes he think about the life in the countryside?

(设计说明:通过提出具体问题, 巩固上一部分的学习内容, 并了解学生掌握知识的程度, 同时培养学生自己组织语言的应变能力。)

S te p3:Cons olidation

1.Listen to 1a again, and then read after it.Imitate the pronunciation and intonation.

2.Let students read 1a and do 1b according to 1a.Finish 1b.

S te p4:Practice

1.Lead to 2a.The teacher shows a picture of a farm and says, “Wang Wei goes to his grandma’s farm every year.He takes many pictures of animals and plants.Look at this picture!There are many animals on the farm.Can you say their names in English?”The teacher leads students to answer and writes down the new words on the blackboard.Master“cow”, “horse”, “hen”, “sheep”, “goose”and“thin”.

2.Let students listen to 2a.Read after the tape and imitate the pronunciation and intonation.

3.Let students read 2a and pick out the sentences which have comparative and superlative degrees of adjectives.For example:

I’m the strongest on this farm.

The pig is stronger than you.

He is lazier than me.

I’m smaller than you.

but I’m faster.

I’m much faster than you.

I’m the biggest of all.

I’m a little bigger than you.

Encourage students to sum up the changing rules of comparative and superlative degrees of adjectives and then the teacher gives additional explanations.Ask students to master the expressions of comparative and superlative degrees of adjiectives.

(设计说明:通过让学生先总结形容词的比较级和最高级的变化规则, 然后教师加以补充, 一步步由浅入深, 锻炼学生的思维和信息处理能力, 发挥他们创造性使用英语的能力, 养成良好的交流合作、互通的学习习惯。)

4.Contest in groups.Lead students make sentences according to the picture in 2a, using the expressions of comparative and superlative degrees of adjectives as much as poossible.

5.Group work.Complete the table in 2b first.Then let students who are wearing the decorative masks of animals role-play the conversation according to 2a, using comparative and superlative degrees of adjectives as much as poossible.Finish 2b.

(设计说明:佩戴面饰的形式, 情趣盎然, 生动活泼, 使学生在轻松、民主的氛围中巩固了知识, 得到了英语语言交际能力的锻炼。)

6.Class activities.The teacherchants with students.Finish 3.

S te p5:Proje ct

Make a survey in groups.Find out how many students like the countryside and how many students like cities in your group.Lead students to compare the countryside with the city.Then each group chooses a representative to make a report to the class.

Requirements:

1.Compare traffics, buildings, life facilities, education and so on.

2.Use comparative and superlative degrees of adjectives as much as possible.

(设计说明:让学生结合生活经历运用所学语言知识, 把课堂的小天地与生活的大课堂结合起来。小组讨论的形式能培养学生合作精神, 并且培养学生的语言组织能力。)

S te p6:Home work