教师姓名 课程名称数学班 级 授课日期 授课顺序 章节名称§2.3 一元二次不等式教 学 目 标知识目标:1、理解一元二次不等式和一元二次方程以及二次函数之间的关系 2、理解一元二次不等式的解集的含义 3、一元二次不等式的解集与二次函数图像的对应 技能目标:1、会解一元二次方程 2、会画二次函数的图像 3、能结合图像写出一元二次不等式的解集 情感目标:体会知识之间的相互关联性,体会数形结合思想的重要性教学 重点 和 难点重点: 1、一元二次不等式的解集的含义 2、一元二次不等式与二次函数的关系 难点: 1、将一元二次不等式和一元二次方程以及二次函数联系起来 2、在函数图像上正确的找到解集对应的部分教 学 资 源《数学》(第一册) 多媒体课件评 估 反 馈课堂提问 课堂练习作 业习题2.3课后记本节课内容是比较重要的,是一元二次方程、一元二次函数、一元二次不等式的结合,相关知识点融会贯通,数形结合的思想方法在这有很好的运用。三种情况只要讲清楚一种,另外两种可由学生自行推出结论。
【教学目标】1、了解方程、不等式、函数的图像之间的联系;2、掌握一元二次不等式的图像解法;【教学重点】1、 方程、不等式、函数的图像之间的联系;2、 一元二次不等式的解法。【教学难点】 一元二次不等式的解法。【教学设计】 1、从复习一次函数图像、一元一次方程、一元一次不等式的联系入手;2、类比观察一元二次函数图像,得到一元二次不等式的图像解法;3、加强知识的巩固与练习,培养学生的数学思维能力。【课时安排】 2课时(90分钟)【教学过程】一、一元二次不等式的解法² 复习回顾1、根据初中所学知识,填写下面表格: △>0 △=0△<0y=ax²+bx+c (a>0)的图像ax²+bx+c=0 (a>0)的根有 2 个根有 1 个根有 0 个根2、观察二次函数y=x²-5x+6的图像,回答下列问题:(1)当y=0时,x取什么值?(2)二次函数y=x²-5x+6的图像与x轴交点的坐标是什么?(3)当y<0时,x的取值范围是什么?总结:由此看到,通过对函数y=x²-5x+6的图像的研究,可以求出不等式x²-5x+6>0与x²-5x+6<0的解集
(三)说目标鉴于以上学情分析,结合单元学习任务群——思辨性阅读与表达的定位,确定本课教学目标为通过设置任务情境,带领学生在活动中认识表达的有针对性、论述的层次逻辑性以及感受文章蕴含的批判力量。其中以表达的有针对性为教学重点,以论述的层次逻辑性为难点。(四)说理念根据课标和教材特点,结合学情,授课将依托“学为中学理论”“建构主义学习理论”和“最近发展区理论”等,积极开展阅读与鉴赏、表达与交流、梳理与探究等语文实践活动提升学生语文核心素养。三、教学实施(一)设定学习情境为引导广大学生合理对待外来文化,学校辩论社拟设定辩题——如何正确对待外来文化展开辩论。有同学说坚决抵制外来文化(正方),也有同学说要积极吸收(反方)……那么如果你是其中一位辩手,你将在《拿来主义》中如何撷取素材呢?
一、说目标本课我制定的教学目标有三:1.学习《荷塘月色》中细腻、传神的语言,体会新鲜贴切的比喻、通感所产生的表达效果。2.通过朗读、品读、赏读,掌握《荷塘月色》描写景物及情景交融的写法,体会其严谨的结构。3.了解心中情和笔下景,体会本文感性与理性交织构成的独特情致,培养学生高尚的审美情趣。我确定以上目标的依据有三:一是基于对新课标的理解:新的语文课程标准在阅读上的要求是“感受文学形象,品味文学作品语言和艺术技巧的表现力,初步鉴赏文学作品。”二是基于对教材的认识:《荷塘月色》作为本单元第一篇课文,承担着奠定基础的任务,即帮助学生通过阅读本课,理解和明确散文应该“读什么”和学会散文应该“怎么读”,然后在学习《故都的秋》和《囚绿记》的过程中去实践、检验、修正,不断增强散文鉴赏的能力,从而提高审美情趣。
(三)以读带讲,感知文本1.学生朗读首先我会让学生结合书下的注释自由大声的朗读本篇课文,扫清文字障碍,感知词意。此环节可以让学生在诵读中解决词中的生字困难,疏通文意。2.教师范读我会声情并茂、感情充沛的进行配乐朗诵。此环节力求让学生感受到词的音乐美,懂得词的朗诵方法,为深入理解词的内容做准备。(四)精讲细读,深入文本此环节主要解决本课的重点,所以我会运用合作教学法和点拨教学法引导学生分析词中典故,探讨作者写作目的。首先我将学生分为孙权刘裕组、刘义隆组、拓跋焘组、廉颇组四个小组。然后对这四个小组分别提出思考问题,让学生以小组为单位解决我提出的问题。在学生讨论结束后分别找每个小组中的一位同学回答,并引导点拨学生答案。孙权刘裕组:
三、课堂检测:(一)、判断题(是一无二次方程的在括号内划“√”,不是一元二次方程的,在括号内划“×”)1. 5x2+1=0 ( ) 2. 3x2+ +1=0 ( )3. 4x2=ax(其中a为常数) ( ) 4.2x2+3x=0 ( )5. =2x ( ) 6. =2x ( ) (二)、填空题.1.方程5(x2- x+1)=-3 x+2的一般形式是__________,其二次项是__________,一次项是__________,常数项是__________.2.如果方程ax2+5=(x+2)(x-1)是关于x的一元二次方程,则a__________.3.关于x的方程(m-4)x2+(m+4)x+2m+3=0,当m__________时,是一元二次方程,当m__________时,是一元一次方程。四、学习体会:五、课后作业
The topic of this part is “Write about your festival experience”.During the Listening and Speaking and Talking, students are just asked to say out their festival experiences such as the Spring Festival, Mid-autumn Day, but this part students will be asked to write down their own festival experiences. During the reading part, it introduces the Naadam Festival in Inner Mongolia Autonomous Region, which can give students a good example to imitate. Students not only learn the festival, but touch and feel the Inner Mongolian’s character, the spirit and cultural atmosphere, which can help students form the cultural awareness and learn to enjoy and value the diversity of Chinese culture.Concretely, the dairy tells the experience that the author spent the Naadam Festival in Inner Mongolia Autonomous Region with his/her friend. The structure is clear. In the opening paragraph, it introduces the topic of the Naadam Festival and the whole feeling. Then it introduces the items of the festival like the ceremony, wrestling and horse racing. Finally, it summarizes this experience. Because this part is a travel journal, we must guide students pay more attention to these details: 1. use the first person. 2. use the past tense to tell the past thing and use the present or future tense to describe the scenery. 3. use the timeline to tell the development. 4. be careful for the author’s psychology, emotion and feeling, etc.1. Read quickly to get main idea; read carefully to get the detailed information about Naadam Festival.2. Learn the structure of the reading article and language.3. Write an article about a festival experience4. Learn to use the psychology, emotions and feeling in the writing.1. Write an article about a festival experience.2. Use the structure of the reading article and language.
Listening and Speaking introduces the topic of “talking about how to become an astronaut”. This period is aimed to inform students some details about the requirements of being an astronaut. Students can be motivated and inspired by the astronauts. Teachers ought to encourage students to learn from them and let them aim high and dream big.Listening and Talking introduces the theme of "talk about life in space". This part also informs students more details about life in space and can inspire students to be curious about this job. 1. Guide students to listen for numbers concerning dates, years and ages etc2. Cultivate students' ability to talk about how to become an astronaut and life in space ; 3. Instruct students to use functional sentences of the dialogue such as “ first of all, I am not sure, so what might be .. I guess.. I wonder…I am curious…)appropriately.1. Guide students to understand the content of listening texts in terms of the whole and key details; 2. Cultivate students' ability to guess the meaning of words in listening; discuss with their peers how to become a qualified astronaut and describe the life in space.Part 1: Listening and SpeakingStep 1: Lead inPredictionThe teacher can ask students to predict what the listening text is about by looking at the pictures.About how to become an astronaut./the requirements of an astronautStep 2: Then, play the radio which is about an interview a. And after finishing listening for the first time, the students need to solve the following tasks.
Q4: What is the function of the International exploration ?Having astronauts from different countries on boardQ5: What can you learn from Para 4 ?China has made great achievements in exploring spaceQ6: What is the attitude to the space exploration ?SupportiveStep 6 Post reading---RetellPeople have always wanted to learn more about space. Before the mid-20th century, most people felt (1)_________ (travel) into space was an impossible dream. However, (2)____ the help of scientists, peoplesucceeded in realizing their dream (3) _________ (explore) space. On 4 October 1957, the Sputnik 1 satellite (4) ____________(launch) by the USSR. (5) ________________ scientists try to make sure nothing goes wrong, accidents can still happen. These disasters made everyone(6)___________(disappoint), but people still believe in the importance of (7) ________(carry) on space exploration. In 2003, China became the third country to (8)_____________ (independent) send humans into space. Then Shenzhou 6 and 7 completed (9)____ second manned orbit and the first Chinese spacewalk. In spite of the difficulties, scientists hope future (10)__________ (discovery) will not only enable us to understand the universe but also help us survive well into the future.Answers: 1. travelling 2. with 3. to explore 4. was launched 5. Although6. disappointed 7. carrying 8. independently 9. a 10. discoveriesStep 6 Post reading---Critical thinkingQ1: What do you think of the space exploration ? I think it is beneficial to us. Through further study of space, people will make full use of it in the future, such as the space experiments by Wang Yaping in Tian Gong 1.Q2: If you are determined to be an astronaut, what should you prepare at present ?First of all, I should study hard to get a related college degree. Besides, I must keep mental and physical healthy.Step 7. HomeworkTry to summarize the structure of the article by a mind map.
另一方面,其余的人反对这个计划,因为它可能会导致一些不好的影响。7.I hold the belief that space exploration not only enable us to understand how the universe began but also help us survived well into the future.我坚信探索太空不仅能够使我们了解宇宙的起源而且能够帮助我们更好地走进未来。8.I think we should spend more time and money exploring space so as to provide new and better solutions to people's shortterm and longterm problems.为了给人类的短期和长期问题提供更新和更好的解决方法,我认为我们应该花更多的时间和金钱来探索太空。9.From my point of view,it is wrong of young people to depend on their telephones too much,which may do harm to both their physical and mental health.在我看来,年轻人过度依赖手机是不对的,因为它们可能会对他们的身心健康都有害。最近你班同学就“人类是否应该进行宇宙探索”这个问题进行了激烈的讨论。有人认为,探索宇宙不仅让人类更好地了解宇宙的发展,还可以用来指导农业生产,以及把一些探索太空的高新技术用于现实生活;也有一些人认为探索太空花掉了大量的人力物力;影响了人们的生活水平。请你根据以下情况写一篇报告并发表自己的观点。注意:1.写作内容应包括以上全部要点,可适当发挥,使上下文连贯;
Everybody wants to get wealth.In today’s material world,making money or becoming wealthy symbolizes a person’s success and capability. Many people just make every effort, pay any price to attain greater wealth. With money,they can buy nice, large apartments in nice neighborhood. With money they can own luxurious cars. Wealth seems to bring all happiness in life.But is wealth the only road to happiness? Not really. There are many things in the world, which are beyond the means of money, such as friendship, love, health and knowledge. People are so preoccupied with struggling for money that they have no time or would not take the time to form or maintain friendship. What happiness can they feel living as lonely miserable creatures without love or friends in the world even if they accumulate tremendous wealth?In my opinion, people can’t do anything without money, but money is not everything. What money will bring you depends on your personal belief and goal in life. If you are kind enough to help others, especially the poor, money is a good thing to you. With it, you can do much more for the benefit of people and your country, and it will add to your own happiness. If you want money just for your own needs, you’ll never be satisfied or happy. In a word,you should have money spent for more people. Only then can money be the source of your happiness.Step 8 Homework4 students in a group, one acts Roderick, one Oliver, one servant and the fourth one acts Henry Adams, then listen to the tape, pay more attention to the difference between American English and British English in pronunciation, stress, tone.
【参考范文】Narrator:(Henry is smiling as he leaves the restaurant. As he is walking down the street, he sees a sign for a place that cuts hair. He decides to get it cut. )H=Henry;B=Barber;R=rude manH:Good afternoon, I'd like to get a cut, if I may. (The barber looks at Henry's hair and continues cutting another man's hair. )Er, I'd really like a haircut. As you can see it's much too long. B:(in a rude manner) Yes, I can see that. Indeed, I can. H:Fine, well I'll have a seat then. (He sits in one of the barber's chairs. The barber turns to look at Henry. )B:It's quite expensive here, you know!Are you sure you can afford it?H:Yes. I think so. (In comes the rude man. )R:Hey you there. I need a haircut quickly. Can you do me straightaway?B:All right, then, get in the chair and I'll see what I can do. R:Thank you. (sits down in one of the barber's chairs)H:Excuse me, but I was here first. Aren't you going to do my hair first?B:This man's in a hurry. H:Well so am I!I insist that you cut my hair first. B:OK, but I'll have to be quick. This gentleman is waiting. H:Thank you. (They both become quiet. After his hair is cut, the barber tells Henry how much he must pay. Henry shows the barber the bank note. )B:Why, Mr . . . (looks shocked)H:Adams. Henry Adams. I'm sorry, I don't have any change. R:You're that Mr Adams! Well,I'm glad I waited or I might never have known it was you. B:Why, Mr Adams, please don't worry!(wearing a big smile) Nothing to worry about!Nothing at all!Please come back any time, even if you only need too little hairs cut!It will be my honour to serve you!
接着引导学生进一步思考截面可不可以是特殊的三角形:等腰三角形和等边三角形。教师用课件演示切截过程,展示切截位置的变化引起截面形状的变化,图形特殊化。使学生的思考经历由一般到特殊的过程。2.截面是其他形状学生先猜想正方体的截面还有可能是什么形状,再利用实验操作型课件对正方体进行无限次的切截,让学生在无限次切截的过程中体会截面产生和变化的整个过程,发现截面产生和变化的规律。学生从切截活动中发现猜想时没有想到的截面图形,体会到探索的乐趣。教师再引导学生归纳正方体截面边数的规律。学生的认知得到升华。接着引导学生归纳截面形状中的特殊四边形。二.圆柱体和圆锥体的截面学生先猜想圆柱体的截面可能是什么形状,教师利用实验操作型课件对圆柱体进行无限次的切截,学生观察截面形状。
我们遇到的往往就是这样的方程组,我们要想比较简捷地把它解出来,就需要转化为同一个未知数系数相同或相反的情形,从而用加减消元法,达到消元的目的.请大家把解答过程写出来.解:①×3,得:6936xy??,③②×2,得:3486??yx,④③-④,得:2?y.将2?y代入①,得:3?x.根据上面几个方程组的解法,请同学们思考下面两个问题:(1)加减消元法解二元一次方程组的基本思路是什么?(2)用加减消元法解二元一次方程组的主要步骤有哪些?(由学生分组讨论、总结并请学生代表发言)[师生共析](1)用加减消元法解二元一次方程组的基本思路仍然是“消元”.(2)用加减法解二元一次方程组的一般步骤是:①变形----找出两个方程中同一个未知数系数的绝对值的最小公倍数,然分别在两个方程的两边乘以适当的数,使所找的未知数的系数相等或互为相反数.②加减消元,得到一个一元一次方程.③解一元一次方程.
③如果某人本月缴所得税19.2元,那么此人本月工资薪金是多少元?根据所给条件写出简单的一次函数表达式是本节课的重点加难点,所以在解决这一问题时及时引导学生总结学习体会,教给学生掌握“从特殊到一般”的认识规律中发现问题的方法。类比出一次函数关系式的一般式的求法,以此突破教学难点。在学习过程中,我巡视并予以个别指导,关注学生的个体发展。经学生分析:(1)当月收入大于1600元而小于2100元时,y=0.05×(x-1600);(2)当x=1760时,y=0.05×(1760-1600)=8(元);(3)设此人本月工资、薪金是x元,则19.2=0.05×(x-1600) X=1984五.教学效果课前:通过本节课的学习,教学目标应该可以基本达成,学生能够理解一次函数和正比例函数的概念,以及它们之间的关系,并能正确识别一次函数解析式,能根据所给条件写出简单的一次函数表达式,且通过本节课的学习学生的抽象思维能力,数学应用能力都能有所提升,
引导学生回忆所学知识。通过这节课的学习你得到什么启示和收获?谈谈你的感受.目的:总结回顾学习内容,有助于学生养成整理知识的习惯;有助于学生在刚刚理解了新知识的基础上,及时把知识系统化、条理化。(四)作业布置加强“教、学”反思,进一步提高“教与学”效果。四、说板书设计采用了如下板书,要点突出,简明清晰。一次函数正比例函数图像的画法:确定两点为(0,0)和(1,K)一次函数选择的两点为:(0,k)和(-b\k,0)五、说课后小结实践证明,在教学中,充分利用教学方法的优势,为学生创造一个好的学习氛围,来引导学生发现问题、分析问题从而解决问题。多媒体课件支撑着整个教学过程,令学生在一个生动有趣的课堂上,能愉快地接受知识
解析:当截面与轴截面平行时,得到的截面的形状为长方形;当截面与轴截面斜交时,得到的截面的形状是椭圆;当截面与轴截面垂直时,得到的截面的形状是圆,所以截面的形状不可能是三角形.故选A.方法总结:用平面去截圆柱时,常见的截面有圆、椭圆、长方形、类似于梯形、类似于拱形等.探究点三:截圆锥问题一竖直平面经过圆锥的顶点截圆锥,所得到的截面形状与下图中相同的是()解析:经过圆锥顶点的平面与圆锥的侧面和底面截得的都是一条线.如图,由图可知得到的截面是一个等腰三角形.故选B.方法总结:用平面去截圆锥,截面的形状可能是三角形、圆、椭圆等.三、板书设计教学过程中,强调学生自主探索和合作交流,经历操作、抽象、归纳、积累等思维过程,从中获得数学知识与技能,发展空间观念和动手操作能力,同时升华学生的情感态度和价值观.
[例3]、用一个平面去截一个几何体,截面形状有圆、三角形,那么这个几何体可能是_________。四、巩固强化:1、一个正方体的截面不可能是( )A、三角形 B、梯形 C、五边形 D、七边形2、用一个平面去截五棱柱,边数最多的截面是_______形.3*、用一个平面去截几何体,若截面是三角形,这个几何体可能是__________________________________________________.4*、用一个平面截一个几何体,如果截面是圆,你能想象出原来的几何体可能是什么吗?如虹截面是三角形呢?5*、如果用一个平面截一个正方体的一个角,剩下的几何体有几个顶点、几条棱、几个面?6*、几何体中的圆台、棱锥都是课外介绍的,所以我们就在这个栏目里继续为大家介绍这两种几何体的截面.(1)圆台用平面截圆台,截面形状会有_____和_______这两种较特殊图形,截法如下:
小刘同学用10元钱购买两种不同的贺卡共8张,单价分别是1元与2元.设1元的贺卡为x张,2元的贺卡为y张,那么x,y所适合的一个方程组是()A.x+y2=10,x+y=8 B.x2+y10=8,x+2y=10C.x+y=10,x+2y=8 D.x+y=8,x+2y=10解析:根据题意可得到两个相等关系:(1)1元贺卡张数+2元贺卡张数=8(张);(2)1元贺卡钱数+2元贺卡钱数=10(元).设1元的贺卡为x张,2元的贺卡为y张,可列方程组为x+y=8,x+2y=10.故选D.方法总结:要判断哪个方程组符合题意,可从题目中找出两个相等关系,然后代入未知数,即可得到方程组,进而得到正确答案.三、板书设计二元一次方程组二元一次方程及其解的定义二元一次方程组及其解的定义列二元一次方程组通过自主探究和合作交流,建立二元一次方程的数学模型,学会逐步掌握基本的数学知识和方法,形成良好的数学思维习惯和应用意识,提高解决问题的能力,感受数学创造的乐趣,增进学好数学的信心,增加对数学较全面的体验和理解.
第一环节:情境引入内容:(一) 情境1实物投影,并呈现问题:在一望无际的呼伦贝尔大草原上,一头老牛和一匹小马驮着包裹吃力地行走着,老牛喘着气吃力地说:“累死我了”,小马说:“你还累,这么大的个,才比我多驮2个.”老牛气不过地说:“哼,我从你背上拿来一个,我的包裹就是你的2倍!”,小马天真而不信地说:“真的?!”同学们,你们能否用数学知识帮助小马解决问题呢?请每个学习小组讨论(讨论2分钟,然后发言).教师注意引导学生设两个未知数,从而得出二元一次方程.这个问题由于涉及到老牛和小马的驮包裹的两个未知数,我们设老牛驮x个包裹,小马驮y个包裹,老牛的包裹数比小马多2个,由此得方程 ,若老牛从小马背上拿来1个包裹,这时老牛的包裹是小马的2倍, 得方程: .
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