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北师大初中九年级数学下册图形面积的最大值1教案
如图所示，要用长20m的铁栏杆，围成一个一面靠墙的长方形花圃，怎么围才能使围成的花圃的面积最大？如果花圃垂直于墙的一边长为xm，花圃的面积为ym2，那么y＝x(20－2x)．试问：x为何值时，才能使y的值最大？二、合作探究探究点一：二次函数y＝ax2＋bx＋c的最值已知二次函数y＝ax2＋4x＋a－1的最小值为2，则a的值为()A．3 B．－1 C．4 D．4或－1解析：∵二次函数y＝ax2＋4x＋a－1有最小值2，∴a＞0，y最小值＝4ac－b24a＝4a（a－1）－424a＝2，整理，得a2－3a－4＝0，解得a＝－1或4.∵a＞0，∴a＝4.故选C.方法总结：求二次函数的最大(小)值有三种方法，第一种是由图象直接得出，第二种是配方法，第三种是公式法．变式训练：见《学练优》本课时练习“课堂达标训练” 第1题探究点二：利用二次函数求图形面积的最大值【类型一】 利用二次函数求矩形面积的最大值
北师大初中九年级数学下册圆内接正多边形教案
解析：正多边形的边心距、半径、边长的一半正好构成直角三角形，根据勾股定理就可以求解．解：(1)设正三角形ABC的中心为O，BC切⊙O于点D，连接OB、OD，则OD⊥BC，BD＝DC＝a.则S圆环＝π·OB2－π·OD2＝πOB2－OD2＝π·BD2＝πa2；(2)只需测出弦BC(或AC，AB)的长；(3)结果一样，即S圆环＝πa2；(4)S圆环＝πa2.方法总结：正多边形的计算，一般是过中心作边的垂线，连接半径，把内切圆半径、外接圆半径、边心距，中心角之间的计算转化为解直角三角形．变式训练：见《学练优》本课时练习“课后巩固提升”第4题【类型四】 圆内接正多边形的实际运用如图①，有一个宝塔，它的地基边缘是周长为26m的正五边形ABCDE(如图②)，点O为中心(下列各题结果精确到0.1m)．(1)求地基的中心到边缘的距离；(2)已知塔的墙体宽为1m，现要在塔的底层中心建一圆形底座的塑像，并且留出最窄处为1.6m的观光通道，问塑像底座的半径最大是多少？
北师大初中九年级数学下册圆周角和圆心角的关系教案
解析：点E是BC︵的中点，根据圆周角定理的推论可得∠BAE＝∠CBE，可证得△BDE∽△ABE，然后由相似三角形的对应边成比例得结论．证明：∵点E是BC︵的中点，即BE︵＝CE︵，∴∠BAE＝∠CBE.∵∠E＝∠E(公共角)，∴△BDE∽△ABE，∴BE∶AE＝DE∶BE，∴BE2＝AE·DE.方法总结：圆周角定理的推论是和角有关系的定理，所以在圆中，解决相似三角形的问题常常考虑此定理．三、板书设计圆周角和圆心角的关系1．圆周角的概念2．圆周角定理3．圆周角定理的推论本节课的重点是圆周角与圆心角的关系，难点是应用所学知识灵活解题．在本节课的教学中，学生对圆周角的概念和“同弧所对的圆周角相等”这一性质较容易掌握，理解起来问题也不大，而对圆周角与圆心角的关系理解起来则相对困难，因此在教学过程中要着重引导学生对这一知识的探索与理解．还有些学生在应用知识解决问题的过程中往往会忽略同弧的问题，在教学过程中要对此予以足够的强调，借助多媒体加以突出.
北师大初中九年级数学下册直线和圆的位置关系及切线的性质教案
解析：(1)由切线的性质得AB⊥BF，因为CD⊥AB，所以CD∥BF，由平行线的性质得∠ADC＝∠F，由圆周角定理的推论得∠ABC＝∠ADC，于是证得∠ABC＝∠F；(2)连接BD.由直径所对的圆周角是直角得∠ADB＝90°，因为∠ABF＝90°，然后运用解直角三角形解答．(1)证明：∵BF为⊙O的切线，∴AB⊥BF.∵CD⊥AB，∴∠ABF＝∠AHD＝90°，∴CD∥BF.∴∠ADC＝∠F.又∵∠ABC＝∠ADC，∴∠ABC＝∠F；(2)解：连接BD，∵AB为⊙O的直径，∴∠ADB＝90°，∴∠A＋∠ABD＝90°.由(1)可知∠ABF＝90°，∴∠ABD＋∠DBF＝90°，∴∠A＝∠DBF.又∵∠A＝∠C，∴∠C＝∠DBF.在Rt△DBF中，sin∠DBF＝sinC＝35，DF＝6，∴BF＝10，∴BD＝8.在Rt△ABD中，sinA＝sinC＝35，BD＝8，∴AB＝403.∴⊙O的半径为203.方法总结：运用切线的性质来进行计算或论证，常通过作辅助线连接圆心和切点，利用垂直构造直角三角形解决有关问题．
中班语言课件教案：耳朵上的绿星星
活动准备：1、制作课件《耳朵上的绿星星》、故事录音带；2、教具：小草、玫瑰花、萤火虫、星星头饰；小松鼠指偶等；3、画有小松鼠图像的画纸（与幼儿人数相等）、幼儿画笔若干。活动过程：一、提出疑问，导入课题孩子们，你们你！小朋友们好！（小松鼠）哦，是小松鼠来了，咦，小松鼠你的耳朵上怎么还有星星呀？星星不是在天上吗？这是怎么回事？小松鼠：听了下面的故事，你们就知道了！请听故事《耳朵上的绿星星》！二、教师有感情的讲述第一遍故事。孩子们，你们说这个故事名字叫什么？（〈耳朵上的绿星星〉）师：小松鼠，我们的孩子说得对吗？小松鼠：对！师：那么，萤火虫为什么跑到你的耳朵上呢？小松鼠：要回答这个问题，先请你们看看我带来的图片吧！师：哟，小松鼠还给我们带了好看的图片，让我们快来看吧。三、播放课件，请小朋友欣赏，教师讲述第二遍故事。1、播放第一部分a、小松鼠上台表演节目，他想怎样来打扮自己b、小松鼠打扮了吗？（没有）为什么c、这件事情让谁看到了？（萤火虫）萤火虫怎么说的?它为什么说小松鼠真好？d、小松鼠没有戴用草编成的帽子、也没有戴用花编成的项链，那他是怎样去参加音乐会呢？2、播放第二部分a、晚上，小松鼠是怎样参加音乐会的？b、是呀！小松鼠一点也没打扮，可是幕布一拉开，台下的观众都惊呆了，他们看到了什么？
新人教版高中英语选修1Unit 4 Body Language教案
本阅读材料的话题是交际中的肢体语言，作者从三个方面讲述了肢体语言的特征与作用，通过主题句和举例阐述的方式让读者了解不同文化中肢体语言的相同或者不同的意义，并从更抽象、概括的维度深入认识肢体语言的特点，理解肢体语言的作用。基于肢体语言的特点，作者提醒读者在与人交流中，尤其是当文化背景有差异的时候，要使用得体的肢体语言，尊重、理解和包容不同的文化，进行有效、有素养的沟通。文本共由六个段落组成，篇章结构为“总—分”。第一段用简练的语言引出了话题，并且从我们自身表达的需要和了解他人感受两个角度讲述了肢体语言的作用。第二段阐述了肢体语言的第一个重要特点——肢体语言在不同的文化中有不同的内涵——这也是文中写作篇幅最大的一个要点，最为重要。通过讲述肢体语言的这一特点，作者向读者传递了要尊重不同的文化、要使用与所在文化相宜的肢体语言。
新人教版高中英语必修1Unit 1 Teenage Life-Discovering Useful Structure教案
（形容词短语most beautiful的构成形式为:副词+形容词，该短语在句中作定语修饰名词bird）④A good friend is someone who makes you really happy.好朋友就是能让你真正高兴的人。（形容词短语really happy的构成形式为:副词+形容词，该短语在句中作宾语补足语）[即学即练]画出下例句中的形容词短语并指明构成形式如:It is less cold today than it was yesterday.构成形式: 副词+形容词（1）Our country is becoming more and more beautiful.（2）The road is long enough.（3）The medicine is good for stomach.三、副词短语（Adverb Phrases）副词短语:指以一个副词为中心构成的短语，在句中的功能相当于副词，可以修饰动词、形容词或副词。常见副词短语的构成形式有:（副词）+副词如: much more beautifully①He did his work here yesterday.他昨天在这里工作。（副词短语here yesterday修饰动词did）②Bill did the work very well.比尔做的这份工作很好。副词短语very well修饰动词did③We are all entirely responsible for our action（副词短语all entirely, 修饰形容词短语responsible for）
新人教版高中英语必修1Unit 1 Teenage Life-Reading and Thinking教案
【教材分析】The topic of this unit is about teenage life, which belongs to the theme context of “humans and oneself”.As teenagers who shoulder the responsibility of “Chinese great dream”, they must fully know themselves, including their strengths, weaknesses and challenges etc. They are supposed to improve themselves continuously and readily study their subjects, and thus foster their strategies and confidence in lifelong studies.This period is entitled the freshmen challenges, which mainly concerns some big challenges for new students in Senior high school. In this period, a teacher should lead students to find out what their challenges are and guide them to figure out how to crack the challenges and better themselves. More importantly, a teacher should instruct students to absorb new language points and appreciate the language. Besides, a teacher must instruct students to acquire some skills concerning reading efficiently and inspire them to talk more about their new school life, especially their new problems and solutions both at school and in life.【教学目标与核心素养】1. Enable students to acquire the basic usage of the new words and expressions concerning the freshmen challenges and learn to use them flexibly.2. Enable students to have a good understanding of the freshmen challenges in the new senior high school which is quite different from junior middle school.3. Develop students’ sense of cooperative learning and individual thinking capability. 4. Develop students’ different learning skills to solve different reading comprehensive problems.
新人教版高中英语必修1Unit 1 Teenage Life-Reading for Writing教案
【教材分析】This teaching period mainly deals with reading for writing a letter of advice. Students are expected to learn the knowledge about how to write a suggestion letter. The teacher is expected to enable students to master some writing skills concerning suggestion letters and learn to write one.【教学目标与核心素养】1. Get students to have a good understanding of how to write a suggestion letter properly.2. Enable students to use some writing skills flexibly.3. Develop students’ writing and cooperating abilities.4. Strengthen students’ great interest in writing discourses.【教学重难点】1. How to enable students to have a good understanding of the skills of writing a suggestion letter2.How to enable students to write a good recommendation letter using some writing skills properly.【教学过程】Step 1: Lead in Begin the class with the lead-in questions: how to write a letter for advice? What kinds of aspects should be included? It is strongly recommended that the teacher should ask students to discuss the topic freely with their partners and brainstorm some ideas concerning the topic. In this way, students can come up with more ideas and avoid being nervous at the beginning of the class.Step 2: Read to discover details concerning advice letters’ writing style.The teacher is expected to ask students to read a letter offering some advice on page 18 silently and then request students to discuss the questions below.
新人教版高中英语必修1Unit 2 Travelling Around-Discovering Useful Structure教案
（5）be to do （可以和具体的时间状语连用）①表示按计划、安排即将发生的动作。②用于时间、条件状语从句中，表示“如果要……，想要……”。The students are to meet at the school gate tomorrow. 明天学生们将在学校大门口集会。 If you are to succeed, you must work as hard as possible. 如果你想要成功，比必须努力工作。（6）be about to do （不与具体的时间状语连用） 表示即将要发生的动作。We are about to start. 我们就要出发了。The new school year is about to begin. 新学年开学在即。（7）一般现在时表将来①表示按时间表规定将要发生的动作。常限于表示位置移动的短暂性动词。②在时间、条件或让步状语从句中，用一般现在时表将来。Look at the timetable. Hurry up! Flight 4026 takes off at 18:20. 你看看时刻表，快点！4026次航班的起飞时间是下午6点20分。Jane is in a hurry because the train to the airport leaves in half an hour. 简很匆忙，因为去机场的火车半小时后出发。
新人教版高中英语必修1Unit 2 Travelling Around–Listening and Speaking教案
无论她说什么都不会对我们的安排有影响。Answers: for, arrangement3) Parents arrange everything for their children and spare no effort to pave the way for their success.父母为孩子安排好一切，不遗余力地为他们的成功铺路。4. extremely adv 极其，非常extreme adj 非常的1) Mary found it extremely difficult to get a job.2) I’m extremely sorry to have troubled you.Answers:玛丽发现找工作极其困难。给你添了麻烦，我十分抱歉。3) It had white-painted tunnels and bright red carriages, and proved _________ (extreme) popular with the public.它有白色的隧道和明亮的红色车厢，结果证明它非常受大众的欢迎。Answers: extremelyExercises1. I am continuing to apply_______ jobs though I have failed several times.2. All this had an _______ (extremely) bad effect on the criminal justice system.3. The invention would have wide ______ (apply) in industry.4. She’s happy with her unusual living _________ (arrange).5. I was banging so loudly that I’m ___________ (amaze) that they didn’t hear me.6. You haven’t changed at all you still look ___________ (exact) the same.7. “Was it what you expected?” “Yes, _________ (definite).”8. He was looking forward to______ (work) with the newPrime Minister. Answers: for extreme application arrangement amazed exactly definitely looking单句写作：1. _______________ (你要说些什么) when you get on the platform to accept the reward?2. Since_____________________(我们为这些事情做好了准备), we have nothing to worry about.
新人教版高中英语必修1Unit 2 Travelling Around-Reading and Thinking教案
Good expressions that students can choose to use: help the travelers choose which tour to take1. In my opinion, you could/might choose…, because you prefer to…2. …could be a perfect choice for you, for…3. As far as I am concerned, you would enjoy…, for…4. …would probably suit you, because you enjoy/love/hate doing…Step 5 Passage ConsolidationLanguage appreciation:1. You can then spend three days exploring the rainforest with a local guide and enjoying the plants and animals unique to the rainforest. 在接下来的三天里，您可以在当地导游的陪同下，深入雨林进行探索，欣赏雨林特有的动植物。本句主体结构为spend some time doing sth. 2. Inca builders cut stones to exact sizes so that nothing was needed to hold walls together other than the perfect fit of the stones. 印加的建筑工人将石头切割成精确的尺寸，仅仅凭着石头间的完美契合，即可稳固墙体。本句为so that引导的结果状语从句。nothing与the perfect fit为并列成分; other than在句中意为“除了”。Step 6 HomeworkSuppose you will travel to Peru, write a short essay about your three-day tour plan.
新人教版高中英语必修1Unit 2 Travelling Around-Reading for Writing教案
Is there a clear purpose for the trip? :Does each paragraph have a clear main idea? Does the writer use the present continuous tense for future plans?Does the writer use commas, stops, and question marks correctly? Are all the words spelt correctly?Are all the proper nouns capitalized?Revise your draft according to your partner's comments.Step 5:The summary of how to write a travel plan.旅游计划是一种常见的应用文写作。旅游可分为观光游、文化游、美食游及探险游等不同类型，因此旅游计划也要根据不同的旅游目的进行设计。常规的旅游计划需要明确以下几个方面的问题:Travel planWhen will you leave for？ Where is your the destination?How will you get there?What will you do there?How long will you there?Is there a clear purpose for the trip? 为了提升旅行计划的层级，还需注意以下几个方面的问题:1.每段是否有明确清晰的主题;2.用一般现在时代替一般将来时；3.用更高级的形容词词汇。例如:表达“好”时，不要总用“nice”,我们还可以用“smart, clean, excellent, exciting, beautiful, wonderful, clever, famous, grand”等表达更具有指向性的词汇；4.用更高级的动词词汇。比如:我们可以用“seem stand, lie .get stay, remain, look . sound, become . keep, grow”等代替"be";
新人教版高中英语必修1Unit 3 Sports and Fitness-Reading and Thinking教案
2. Sort out detailed information about Michael Jordan.（1） Understand the transitional sentence.Q: Which part is about Michael Jordan as a master? Which part is about the example he set?（2） Have the Ss Focus on why Michael Jordan is a master and what good examples Michael Jordan set when they’re reading. And think about these questions as below:Q1: How does the author describe his impressive skills?Q2: How do you understand “time seemed to stand still”?Q3: What does “graceful” mean?Q4. Which sentence do you think best describes his mental strength?Q5. Which words is important in the sentence in describing his mental strength? Why?Q6: How do you understand “unique”?Q7: What can we learn from Michael Jordan?Step 5 Discussing and recommendingRecommend their own living legends of sports.Work in groups to choose your own living legend of sports and give the reasons of your choice. Step 6 HomeworkReview the stories of Lang Ping and Michael Jordan, and try to retell them.
新人教版高中英语必修1Unit 3 Sports and Fitness-Reading for Writing教案
Then have them write a short paragraph to describe and explain their changes. After that, get the Ss to exchange their drafts with their partners and use the checklist to give feedback on their drafts, and finally revise it.Step 5 Summary of how to write a wellness book1.健康书的审题步骤：第一步：明确要求该写作属于经验分享，故要用第一人称来写;时态以一股现在时为主。第二步：确定段落该类文章可以从以下三个方面人手:Para.1首先表明写作的目的Para.2自己的做法及心得体会Para.3表示期望及感谢第三步：提炼要点2.健康书常见句式：1) It is an honor for me to share my favorite sport with you,2) It makes me feel relaxed playing with my friends.3) It makes me rid myself of stress while playing with my friends.4) Moreover, it provides me a valuable chance to communicate with others.5) I we eat too little or too much, or if we choose the wrong food, we may become sick.6) We can do something to change the poor situation.Step 6Homework假如你的老师让你在班级Wellness Bok上分享自己的亲身经历及心得，请根据以下要点写一篇80字左右的文章1. 你喜欢的运动是什么？2. 你最喜欢的原因是什么？3. 你参加锻炼的体会。
新人教版高中英语必修1Unit 4 Natural Disasters- Reading for writing教案
①标题——标题应当简洁明了。②导语——导语是消息开头的第一段或第一句话，简明扼要地揭示出消息的核心内容。③主体——主体是消息的主要部分，要用充足的事实表现主题，对导语的内容作进一步的展开和阐述。④结束语——通常是对全文内容进行概括性的总结。3. 新闻报道增分句子（1）陈述事实常用的句型:①A terrible storm hit/struck ... , killing ..②It was a cool autumn night when the earthquake happened. A large number of buildings fell down and roads were destroyed, leaving a great many people homeless.地震发生在一个凉爽的秋夜。大量的建筑物倒塌，道路被毁,许多人无家可归。③With the help of the rescue team, people who were the trapped in the flood were saved.在救援队的帮助下，困在洪水中的人们得救了。（2）陈述观点常用的句型:①Clearly/Obviously/In my opinion/It seemed that people were shocked.显然/在我看来/似乎人们震惊了。②The whole city was in ruins after the earthquake.地震后整个城市成了一片废墟。（3）揭示原因常用的句型:Because of/As a result of/Thanks to the help of the army, people who got injured were sent to the hospital immediately.
新人教版高中英语必修1Unit 4 Natural Disasters-Discovering Useful Structures教案
【教材分析】This teaching period mainly deals with the grammar: the restrictive relative clauses.This period carries considerable significance to the cultivation of students’ writing competence and lays a solid foundation for the basic appreciation of language beauty. The teacher is expected to enable students to master this period thoroughly and consolidate the knowledge by doing some exercise of good quality.【教学目标与核心素养】1. Get students to have a good understanding of the basic usages of the restrictive relative clauses.2. Enable students to use the restrictive relative clauses flexibly.3. Develop students’ speaking and cooperating abilities.4. Strengthen students’ great interest in grammar learning.【教学重难点】How to enable students to have a good understanding of the restrictive relative clauses, especially the uses of the relative words such as which, that, who, whom.【教学过程】Step1: 语法知识呈现定语从句（一）—关系代词的用法在复合句中, 修饰名词或代词的从句叫定语从句。定语从句通常由关系代词或关系副词引导，说明事物的具体信息，从句位于被修饰词之后。被定语从句修饰的词叫先行词，引导定语从句的词叫关系词，关系词指代先行词，并在定语从句中充当成分。关系词有两种：关系代词who, whom ,whose, that, which, as和关系副词when, where, why。
新人教版高中英语必修1Unit 4 Natural Disasters-Listening and Speaking教案
【教材分析】高考听力材料的选用非常重视语言真实性和交际性的原则，语言材料一般来源于实际生活，对话的内容大都取材于日常生活，即衣、食、住、行、工作、学习、天气、生活环境等话题，可分为校园、公共场所、家庭等方面，如: shopping, finding the way, doing one’s homework, seeing a doctor, making a phone call, weather report, asking for different kinds of information等。新教材的特点就是利用生活中真实文本，只是降低难度，让学生注重语言的应用，将是我们高考把握方向的重要因素。【教学目标与核心素养】学习能力目标：在听力当中，学生应该有效规划学习方法，选择恰当的策略与方法。这节课的训练目标是让学生有正确的预测和抓住问题的关键信息，从而用心去听来找寻关键信息。根据生活中实际情况和高考常见语境，我们不难发现提前预测和抓住题干中的w很重要，即what, where, when, why等等。
新人教版高中英语必修1Welcome Unit-Discovering Useful Structures教案
II Learn the technical terms-2.1. What can be used as “Subject, Object, Predicative, Direct Object, Indirect Object and objective complement” in a sentence?2. What can be used as “adverbial” in a sentence?3. What can be used as “verb” in a sentence?Answers to questions 1-3:1. Nouns, pronouns and appellations can be used as “Subject, Object, Predicative, Direct Object, Indirect Object and Objective Complement”. Besides, adjectives can be used as “Predicative and Objective Complement” in a sentence.2. Adverbs and prepositional phrases can be used as “Adverbial”.3. Verbs with actual meaning can be used as “Verb” in a sentence. Auxiliary verbs alone cannot be used as “Verb” in a sentence.III Learn to recognize the sentence structures.1. SV structure. For Example:(1) A bird flies.S V(2) A monkey jumps.S V(3) A fish swims.S V√ In SV structures, verbs are “intransitive verbs”.2. SVO structure. For Example:(1) A sheep eats grass.S V O(2) They like bananas.S V O(3) He wants candy.S V O√ In SVO structures, verbs are “transitive verbs”.3. SP structure. For Example:(1) This is great.S P (2) He looks well.S P (3) She became a teacher.S P √ In SP structures, Predicatives are formed by “link verbs” and “adjectives or nouns”.√ link verbs: be, become, grow, look, feel, taste, etc.4. SV IO DO structure. For Example:(1) He asked me a question.S V IO DO(2) Danny wrote me a letter.S V IO DO(3) Billy brought Sam a kite.S V IO DO√ In SV IO DO structures, the verbs are transitive and are followed by two objectives – pronouns or nouns as Indirect Objective, and nouns as Direct Objectives.
新人教版高中英语必修1Unit 4 Natural Disasters-Reading & Thinking教案
5. Read to get detailed information about Paragraph 5.Q1. What shows the revival of Tangshan?Q2. How can Tangshan revive itself and get up on its feet again?Q3. In times of disasters, how can we go through it?T: In times of disasters, we should unify, show the wisdom and stay positive.Step 4 Activity 4 Highlighting the theme and reflecting1. Make a summary of the text.2. Further understand the titleQ: After our learning, why do you think the earth didn’t sleep on that night?T: An earthquake happened. The people in the earthquake suffered a lot, and the people outside Tangshan were concerned about the people there a lot.3. Reflect through discussion on what can be learnt after reading.T: Disasters are powerful. Unpreparedness can be deadly. Life is weak, but if people work together to help each other, disasters can be defeated.There is no love from disaster, but we have love in the human heart.Step 5 Assignment How does the writer convey that the earthquake was deadly, and that people were helpless during the earthquake? Try to find some attractive and impressive expressions and note them down.