Good morning, distinguished judges:It’s my honor to talk about my teaching ideas with you. Today my topic is Women of Achievement. My presentation consists of six parts: the analysis of teaching material and student, teaching aims, key and difficult points, teaching and studying method, teaching procedures and blackboard design.First, let’s focus on the analysis of teaching material. This lesson is from New Senior English for China Student’s Book 4 Unit 1, the reading part. The main topic of the passage is the introduction of a student of Africanwildlife. After this lesson, the students will learn more information about her studying chimps in Africa, and their reading and speaking abilities can be developed as well.The next part is the analysis of students. My students are in senior high students. They have learnt English for many years, they’ve known many words and sentences, but their speaking and reading abilities are still not very good. So I will practice their speaking and reading abilities through different exercises.According to the New Standard Curriculum and the present situation, I set the teaching aims as follows: firstly, knowledge aims. Students can grasp some new words, such as worthwhile, move off. Moreover, students can understand the content of the passage and get familiar with the topic of studying chimps in wildlife. Secondly, ability aims. Students can use reading strategies such as skimming and scanning in reading process. Thirdly, emotional aims. Students can have the awareness of protecting animals and care about animals.Based on the above analysis, the key point of this lesson is to get the main idea and the detailed information from the passage; the difficult point is to talk about the wildlife protection and use reading strategies.
Teaching plan for Unit 1 book3Good morning, teachers. It’s my great pleasure to be here because I can share my lesson with you and I can learn a lot from it. I’ll begin my lesson from the following four parts, the teaching material, the teaching methods, the studying methods and the teaching procedure.Firstly, let me talk about the teaching material. The content of my lesson is the reading passage festivals and celebrations of Unit 1 Festivals around the world. This passage is about festivals and celebrations. By studying this passage, we’ll enable the students to know that festivals exit everywhere, and many of festivals in different countries celebrate similar ideas. As we all know, the reading passage is the center of each unit. If the Ss can learn it well, it will be helpful to make the Ss learn the rest of this unit.After studying the teaching material, I think the teaching aims are as the followings:1. Knowledge aims:(1) The Ss can master the usage of the important words andexpressions.(2)The Ss can use the __________________ (grammar) in the proper situation.Make students know about the festivals all over the world and the detail of the festivals, such as origin, content, and the date of the holiday festivals.2. Ability aims:(1) Students can talk about festivals and celebrations in English(2) To improve the student’s reading ability, especially their skimming and scanning ability.3. Emotion aims:Make the Ss know about the foreign festivals, and respect other countries’ custom.Next, let’s come to the important points and the difficult points.The important point is how to make the Ss understand the text better and the difficult point is how can they talk about it. secondly, Teaching Methods:1. task-based Language Teaching2. Computer assisted language teaching.3. question-and–answer methodThirdly, Studying Methods:
The oldest and the most popular park in the worldenjoy the exciting activities thereget close to the life-size cartoon characters like Mickey Mouse and Donald Duck Step 3 Pre-reading1.What do you suppose a theme park is ?2.What do you think you can see in a theme park?(1.It is a kind of amusement park which has a certain theme – that the whole park is based on. 2.buildings, castles, statues, rare animals and birds, and so on.) Step 4 Reading ----- Theme Parks –---- Fun and More Than Fun1.Predict : Read the title and the pictures on P. 34 and PredictWhat is the meaning of the title “Theme Park – Fun and more than fun”?(The title means that theme parks are fun to visit, but that they can also be educational and can offer useful information.)2.Skimming Fast read and answer:What activities can we take in a theme park?Amusement park: Bumper car Merry-go-round slide bungee jumping Free-fall rides Horror films Pirate ship Ferris wheel roller coaster3.Scanning Read again and you will find various theme parks are mentioned in the passage . Then what are they ?Theme parks: Sports theme park History theme park Culture theme park Marine or Ocean theme Park Future park Science theme park Disneyland4.Careful reading and find the main idea of each paragraph:THEME PARKS---- entertaining/ educationalPara.1 Traditional parks are places to go for relaxation and to have time away from our busy lives.Para.2 Theme parks are different They’re large and full of things to do, see and buy.Para.3 Theme parks are built around a single idea or theme. One example is a sports park.Para.4 Another kind of theme park is historical more and cultural and can be educational.Para.5 Disneylandwas the first theme park. It is based on the fantasy life and characters of Disney’s films.Para.6 Some examples of educational theme parks include sea world parks and science parks.
Language learning needs a context, which can help the learners to understand the language and then can product comprehensible output, so computer has the advantages to make the materials attractive.Part 3 Learning MethodsTask-based, self-dependent and cooperative learningPart 4 Teaching ProcedureStep One Lead-in“Interest is the best teacher.” Therefore, at the very beginning of the class, I should spark the students’ mind to focus on the centre topic “the band”. I’ll show some pictures of food to attract their attention and then bring some questions.Question:What kind of food they like?What should go into a good meal?The answers must relate to the diet. After this, the students will be eager to know something about a balance diet and this is the very time to naturally lead the class into Step 2Step 2 Reading for information: skimming and scanning In this step, I use Task-based Language Teaching method, which can give students a clear and specific purpose while skimming and scanning the context.Task 1 General ideaThe students will be asked to just glance at the title and the pictures of the passage, and then guess what they will read in the text. And they’ll be divided into groups of four to have a discussion.The purpose is to inspire the students to read actively, not passively. In addition, the task is to develop the students’ reading skill by making prediction and to encourage the students to express their thoughts in English and cooperate with each other.Task 2 Main idea of each paragraphCooperative learning can raise the students’ interest and create an atmosphere of achievement. Based on this theory, I divide the whole class into 4 groups to skim the whole text and get the main idea of each paragraph.
Knowledge objectives:(1) to make Ss grasp the usage of words, expressions and sentence structures: statistics, struggle, thanks to, rid of, some patterns for persuasion, the “ing” form as subject and object;(2)to use learnt knowledge to persuade sb.Ability objectives:(1) to develop Ss’ reading skills(skimming, scanning, word guessing);(2) to improve Ss’ speaking, communicating and cooperating skills.Emotional objectives:to make Ss know the contribution of Yuan,and learn his spirit and his simple life time.Teaching important and difficult points:(1) some words, expressions and sentence structures mentioned above;(2)the content of the text;(3)training their reading and speaking skills.Teaching methods: CLT, TBLT,QT.Learning strategies: CLS, QLS, TBLS.Teaching procedures:Step 1 lead-in: (1) teacher plays a piece of recent news from CCTV about the harvest of the super hybrid rice, and ask students whether they know Yuan or not, and talk about him and his contribution.(2)Brain storm: let Ss describe Yuan in their minds including his appearance, his living condition and so on.Step 2 fast reading tasks:(1)teacher introduces Yuan and super hybrid rice(2)make Ss read the text as fast as possible with questions. Such as: what’s the general ideaof this passage? What’s Yuan’ dream? (skimming and scanning skill)Step 3 intensive reading tasks(1)let Ss read the text silently, find topic sentence of each paragraph and draw the difficult sentences and the knowledge what they don’t understand.(words guessing)(2)teacher and Ss talk about the important words, expressions and sentences together, and ask Ss to retell the content of the text.(summarizing and paraphrasing)(3)teacher summarize this part.(4) read again following the courseware.
在接下來的細(xì)讀環(huán)節(jié),我套用了高考對(duì)閱讀理解的考查方式設(shè)置了5個(gè)問題,分別為三個(gè)推理判斷題,一個(gè)細(xì)節(jié)題和一個(gè)主旨大意題。學(xué)生需要對(duì)文章的內(nèi)容進(jìn)行分析、歸納、推理、猜測等高級(jí)思維活動(dòng)才能做出正確的回答。【設(shè)計(jì)意圖】這一過程是對(duì)學(xué)生進(jìn)行細(xì)讀的訓(xùn)練,培養(yǎng)學(xué)生獲取特定信息和挖掘文章深層次信息的能力。第三環(huán)節(jié):Intensive-reading (精讀) 15′第三個(gè)環(huán)節(jié)精讀,既是最重要的環(huán)節(jié),也是突破本課重難點(diǎn)的關(guān)鍵。首先,讓學(xué)生思考劇本中人物看到百萬英鎊前后的態(tài)度發(fā)生了怎樣的變化。其次,讓學(xué)生仔細(xì)閱讀文章,找出可以表現(xiàn)人物態(tài)度變化的具體的語言和動(dòng)作。最后,讓學(xué)生總結(jié)人物的態(tài)度發(fā)生變化的根本原因是什么,從而引出Money Talks, 供學(xué)生思考?!驹O(shè)計(jì)意圖】通過一系列的活動(dòng)培養(yǎng)學(xué)生學(xué)習(xí)從人物的語言和動(dòng)作探究人物的心理,使學(xué)生進(jìn)一步體會(huì)戲劇語言的魅力,從而對(duì)文章背后所反映的社會(huì)問題進(jìn)行思考,也為下一步的討論環(huán)節(jié)做好鋪墊。
In this class, I have 3 teaching aims, that is, knowledge aims, ability aims and emotion aims.1) Knowledge-Teach students new words and expressions, such as temporary, bleed,sprain choke, first aid, fall ill and so on.-Enable students to have a better understanding for some basic knowledge of first aid.2) Ability-Train students’ speaking, reading and writing abilities by different teaching activities, such as skimming, comprehending, team work, role play, retelling and writing.-Develop students’ reading strategy on how to move general idea to specific information.3) Emotion-Promote students’ awareness of giving first aid.- Cultivate students’ creativities.Then let’s come to my teaching methods and activities.III. Teaching methods and activities:To achieve different teaching aims, various kinds of teaching methods and activities will be adopted throughout this period, such as TBL (task-based learning), skimming, team work, brainstorm and others, which can offer students opportunities to fulfill tasks in which they can use language to achieve a specific outcome.IV. Teaching aids:Computer and blackboardV. Teaching important points:1) Make students have a clear mind for the structure of the text.2) Help students understand the theme of the text.VI. Teaching difficulties:1) So many new words may affect students’ understanding.2) How to get students to know about the functions of the skin and thecauses, characteristics and treatments for different degree burns,and the knowledge about giving first aid. VII. Blackboard design:
通過寫文章梗概,培養(yǎng)學(xué)生綜合運(yùn)用語言的能力,學(xué)習(xí)用恰當(dāng)?shù)挠⒄Z描述科學(xué)家的故事。這是本課的教學(xué)難點(diǎn)。教師可以使用完形填空的方式來幫助學(xué)生整理語篇,從而來降低難度。本課的教學(xué)重點(diǎn)的突破方法是:在閱讀前,讓學(xué)生初步了解得出科學(xué)觀點(diǎn)所需要的基本程序,從而輕松而自然地導(dǎo)入文章的閱讀;在閱讀過程中,由易到難設(shè)計(jì)快速閱讀和精讀的問題,層層推進(jìn)各種閱讀活動(dòng),讓學(xué)生對(duì)閱讀內(nèi)容從整體感知到細(xì)節(jié)理解,最后深層讀懂整篇文章,同時(shí)加強(qiáng)閱讀策略的指導(dǎo),讓每個(gè)學(xué)生都主動(dòng)參與課堂教學(xué)活動(dòng),最終達(dá)到提高閱讀能力的目的。Step 4 Post-readingGroup Activities四人小組共同合作,在老師的適當(dāng)指導(dǎo)下,就以下2個(gè)問題展開討論,讓學(xué)生就所知、所學(xué)、所感和所想融入話題,然后抽若干同學(xué)代表作小組發(fā)言。1. What do you think about John Snow, and what should we learn from him?2. Cholera was 19th century disease, which two diseases are similar to cholera today? Why?
Good afternoon, everyone. It’s my great pleasure to be here sharing my lesson with you. The content of my lesson is Senior English for China Book5 Unit 3 Life in the Future. I’ll be ready to begin this lesson from six parts: Analysis of the teaching material, Analysis of the students, Teaching aims and important and difficult points, Teaching methods and aids, Teaching procedures, and Blackboard design. First, let me talk about the teaching material.Part 1 Analysis of the Teaching Material:This unit is about what human beings’ life will be like in about one thousand years. By studying of this unit, we’ll Enable the students to know the changes in humans’ life and some new inventions bringing about the change and develop the interest in science. This lesson plays an important part in the English teaching in this unit. This is an important lesson in Book Five. From this lesson, it starts asking the Ss to grasp contents of each passage. Therefore, this lesson is in the important position of the teaching material. If the Ss can learn it well, it will be helpful to make the Ss learn the rest of this unit.Part 2 Analysis of the SsAs Senior2 Ss, they are at different levels of English fluency, some of them have lost interest in English. So during the lesson, I arrange a variety of activities to let all of them join in to attract their interest and let them be confident and taste the joy of success.
今天我們來介紹一下必修五第四單元的授課方式。這個(gè)單元的題目是Making the news。應(yīng)該是學(xué)生比較感興趣的話題,學(xué)生往往對(duì)新聞工作充滿好奇,所以我們可以利用這個(gè)機(jī)會(huì)多設(shè)計(jì)一些師生互動(dòng)和學(xué)生互動(dòng),來激發(fā)起學(xué)習(xí)的積極性,提高學(xué)習(xí)效率。同時(shí)我們可以利用這個(gè)單元不僅幫助學(xué)生掌握語言知識(shí),培養(yǎng)語言能力,同時(shí)讓其了解新聞工作的重要性,培養(yǎng)起社會(huì)智能感。這個(gè)單元分為六個(gè)課時(shí),它的教學(xué)目標(biāo)是這樣的:語言目標(biāo)是掌握詞匯表中的常用單詞和短語,掌握倒裝句的一些基本用法。 技能目標(biāo)是能初步掌握約會(huì)的基本句型并在真實(shí)的場景下正確運(yùn)用。新聞報(bào)道類文章的寫作技能。采訪的基本規(guī)范和溝通技能。情感目標(biāo)是對(duì)新聞報(bào)道的客觀性和真實(shí)性有更好的理解。對(duì)新聞?dòng)浾叩穆殬I(yè)有更深入的了解,并能體會(huì)其工作的重要性。下面我們來介紹一下第一課時(shí)的授課方式,第一課的教學(xué)目標(biāo)是這樣的第一課時(shí)的教學(xué)目標(biāo)語言目標(biāo):單詞:Occupation, journalist, editor, photographer, curious, personality, enthusiasm
Teaching Aims:Knowledge 1. Get the students to learn the useful new words and expressions in this section. Aims:2. Let the students learn about how the UK was formed and the four groups of invaders.1. Develop students’ reading ability and let them learn different Ability reading skills. Aims:2. Enable students to learn to talk about the United Kingdom and the Union Jack Emotional 1. Let students know more about the UK2. Develop students’ sense of cooperative learning Aims:Teaching Important Points:1. Let the students learn about the countries of the United Kingdom and the Union Jack2. Get the students to read the passage and know about how the UK was formed and the four groups of invaders.3. Have the students learn different reading skills.Teaching Difficult Ponts:1. Develop students’ reading ability.2. Enable students to talk about the United Kingdom and the Union Jack.3. Let students learn how the UK was formed geographically and historically.Teaching Methods:Showing pictures, asking, exercising, listening, reading etc.Teaching Aids:A computer,a projector and a blackboard.Teaching Procedures: 1) Show a map of the world, ask students the following questions:Where is the UK?What’s the full name of the UK?2) Ask the students work in pairs to do the quiz on Page 9.Do you want to test how many things you know about the United Kingdom? Let’s have a small test.Using the map on P9, students answer the following questions:?How many countries does the UK consist of? What are they??England is divided into three main areas. Do you know what they are? 1) Scanning (10Minutes )Let the students hold the questions asked in pre-reading and read the passagequickly and then let them do the following exercise.Join lines to the right answer.
演講稿頻道《國旗下的講話稿范文:讓運(yùn)動(dòng)成為習(xí)慣》,希望大家喜歡。親愛的老師、同學(xué)們:大家早上好!很榮幸能在這陽光明媚的早晨,在親切而壯嚴(yán)的國旗下做演講。今天我演講的題目是“讓運(yùn)動(dòng)成為習(xí)慣”。我國古代的醫(yī)學(xué)家華佗認(rèn)為:生命在于運(yùn)動(dòng);而民間也有更為直白的俗語說道:人勤病就懶,人懶病就勤。說得其實(shí)是一個(gè)意思,就是健康的身體需要運(yùn)動(dòng)來保證,而人生的財(cái)富正是健康。所以,要想擁有這筆財(cái)富,的方法就是:讓運(yùn)動(dòng)成為習(xí)慣。如今,美麗的校園正給我們提供了這樣的條件,寬廣的綠茵場給了大家一個(gè)充分展現(xiàn)自我的空間。每天下午,放下手中的功課,跑上兩圈,揮灑一些汗水,倦意便頓時(shí)消失,不僅達(dá)到了勞逸結(jié)合的效果,也豐富了我們的課余生活。若長期堅(jiān)持下去,必將使我們的體魄有所增強(qiáng),從而有利于我們以更好的狀態(tài)投入學(xué)習(xí)活動(dòng)中去。然而,有些同學(xué)則認(rèn)為體育鍛練是浪費(fèi)時(shí)間,認(rèn)為分秒必奪的讀書學(xué)習(xí)才是硬道理。他們無論早晨、下午甚至是體育課上都捧著書抓緊學(xué)習(xí)。他們犧牲的是運(yùn)動(dòng)的時(shí)間,得到的是短期內(nèi)學(xué)習(xí)成績的提升。
教學(xué)過程:(一)導(dǎo)入:課前放《愛的奉獻(xiàn)》歌曲,同時(shí)不斷播放一些有關(guān)“愛”的主題的圖片,渲染一種情感氛圍。師說:同學(xué)們,誰能說說這組圖片的主題應(yīng)該是什么?生(七嘴八舌):母愛,不對(duì)是親情……是友情、還有人與人互相幫助……那組軍人圖片是說保衛(wèi)國家,應(yīng)該是愛國……那徐本禹和感動(dòng)中國呢?…………生答:是關(guān)于愛的方面師說:不錯(cuò),是關(guān)于愛的方面。那么同學(xué)們,今天就以“愛的奉獻(xiàn)”為話題,來寫一篇議論文如何?生答:老師,還是寫記敘文吧。生答:就是,要不議論文寫出來也象記敘文。師問:為什么?生答:老師,這個(gè)話題太有話說了,一舉例子就收不住了,怎么看怎么象記敘文。生答:就是,再用一點(diǎn)形容詞,就更象了。眾人樂。師說:那么同學(xué)們誰能告訴我,為什么會(huì)出現(xiàn)這種問題?一生小聲說:還不是我們笨,不會(huì)寫。師說:不是笨,也不是不會(huì)寫,你們想為什么記敘文就會(huì)寫,一到議論文就不會(huì)了,那是因?yàn)橥瑢W(xué)們沒有明白議論文中的記敘與記敘文中的記敘有什么不同,所以一寫起議論文中的記敘,還是按照記敘文的寫法寫作,這自然就不行了。那好,今天我們就從如何寫議論文中的記敘講起。
(二)能力目標(biāo)培養(yǎng)學(xué)生運(yùn)用哲學(xué)理論觀察、分析、處理社會(huì)問題的能力,增強(qiáng)學(xué)生的時(shí)代感。(三)情感、態(tài)度與價(jià)值觀目標(biāo)培養(yǎng)學(xué)生與時(shí)俱進(jìn)的思想品質(zhì),讓學(xué)生關(guān)注時(shí)代、關(guān)注現(xiàn)實(shí)、關(guān)注生活,逐步樹立科學(xué)的世界觀、人生觀、價(jià)值觀。三、說教學(xué)重難點(diǎn):時(shí)代精神的總結(jié)和升華是本框的難點(diǎn),雖然學(xué)生在文化生活中學(xué)習(xí)了文化與經(jīng)濟(jì)政治的關(guān)系,但要讓學(xué)生得出哲學(xué)是時(shí)代精神的總結(jié)和升華,還要聯(lián)系前面關(guān)于哲學(xué)的基礎(chǔ)知識(shí)進(jìn)行總結(jié)歸納,因此可能會(huì)難以把握,另外關(guān)于什么樣的哲學(xué)是真正的哲學(xué)的理解會(huì)稍有難度。社會(huì)變革的先導(dǎo)是本框的重點(diǎn),一方面哲學(xué)源于時(shí)代,另一方面強(qiáng)調(diào)哲學(xué)反過來對(duì)時(shí)代又有重要的反作用,突出這一點(diǎn)能夠更好地激發(fā)學(xué)生學(xué)習(xí)哲學(xué)的熱情和信心,對(duì)于后面知識(shí)的學(xué)習(xí)是極為有益的,因此社會(huì)變革的先導(dǎo)這一目作重點(diǎn)處理。
本節(jié)是新人教A版高中數(shù)學(xué)必修1第1章第1節(jié)第3部分的內(nèi)容。在此之前,學(xué)生已學(xué)習(xí)了集合的含義以及集合與集合之間的基本關(guān)系,這為學(xué)習(xí)本節(jié)內(nèi)容打下了基礎(chǔ)。本節(jié)內(nèi)容主要介紹集合的基本運(yùn)算一并集、交集、補(bǔ)集。是對(duì)集合基木知識(shí)的深入研究。在此,通過適當(dāng)?shù)膯栴}情境,使學(xué)生感受、認(rèn)識(shí)并掌握集合的三種基本運(yùn)算。本節(jié)內(nèi)容是函數(shù)、方程、不等式的基礎(chǔ),在教材中起著承上啟下的作用。本節(jié)內(nèi)容是高中數(shù)學(xué)的主要內(nèi)容,也是高考的對(duì)象,在實(shí)踐中應(yīng)用廣泛,是高中學(xué)生必須掌握的重點(diǎn)。A.理解兩個(gè)集合的并集與交集的含義,會(huì)求簡單集合的交、并運(yùn)算;B.理解補(bǔ)集的含義,會(huì)求給定子集的補(bǔ)集;C.能使用 圖表示集合的關(guān)系及運(yùn)算。 1.數(shù)學(xué)抽象:集合交集、并集、補(bǔ)集的含義;2.數(shù)學(xué)運(yùn)算:集合的運(yùn)算;3.直觀想象:用 圖、數(shù)軸表示集合的關(guān)系及運(yùn)算。
一、教材分析下面我來談一談對(duì)教材的認(rèn)識(shí):主要從教材的地位和作用、以及在此基礎(chǔ)上確立的教學(xué)目標(biāo)、教學(xué)重難點(diǎn)這三個(gè)方面來談。首先,來談教材的地位和作用:本課教材內(nèi)容主要從三個(gè)方面向?qū)W生介紹了現(xiàn)代中國教育的發(fā)展?fàn)顩r和趨勢(shì):人民教育的奠基、動(dòng)亂中的教育和教育的復(fù)興,全面講述了新中國教育的三個(gè)階段。本課是文化史中中國史部分的最后一課, 也是必修三冊(cè)書中唯一涉及教育的一課。而教育是思想文化史中的重要組成部分,江澤民同志在談到教育的時(shí)候曾經(jīng)說過,“百年大計(jì),教育為本。教育為本,在于育人”。教育是關(guān)系國計(jì)民生的大事。學(xué)生通過學(xué)習(xí)新中國教育發(fā)展的史實(shí),理解“科教興國”、“國運(yùn)興衰,系于教育”的深刻含義。最終由此激發(fā)學(xué)生樹立“知識(shí)改變命運(yùn)、讀書成就人生”的信念,樹立勤奮學(xué)習(xí)、成人成才、報(bào)效祖國、服務(wù)社會(huì)的崇高理想。故本課的教學(xué)有極大的現(xiàn)實(shí)意義。談完了教材的地位和作用,我再分析一下教學(xué)目標(biāo):
二、典例解析例3.某公司購置了一臺(tái)價(jià)值為220萬元的設(shè)備,隨著設(shè)備在使用過程中老化,其價(jià)值會(huì)逐年減少.經(jīng)驗(yàn)表明,每經(jīng)過一年其價(jià)值會(huì)減少d(d為正常數(shù))萬元.已知這臺(tái)設(shè)備的使用年限為10年,超過10年 ,它的價(jià)值將低于購進(jìn)價(jià)值的5%,設(shè)備將報(bào)廢.請(qǐng)確定d的范圍.分析:該設(shè)備使用n年后的價(jià)值構(gòu)成數(shù)列{an},由題意可知,an=an-1-d (n≥2). 即:an-an-1=-d.所以{an}為公差為-d的等差數(shù)列.10年之內(nèi)(含10年),該設(shè)備的價(jià)值不小于(220×5%=)11萬元;10年后,該設(shè)備的價(jià)值需小于11萬元.利用{an}的通項(xiàng)公式列不等式求解.解:設(shè)使用n年后,這臺(tái)設(shè)備的價(jià)值為an萬元,則可得數(shù)列{an}.由已知條件,得an=an-1-d(n≥2).所以數(shù)列{an}是一個(gè)公差為-d的等差數(shù)列.因?yàn)閍1=220-d,所以an=220-d+(n-1)(-d)=220-nd. 由題意,得a10≥11,a11<11. 即:{█("220-10d≥11" @"220-11d<11" )┤解得19<d≤20.9所以,d的求值范圍為19<d≤20.9
二、典例解析例10. 如圖,正方形ABCD 的邊長為5cm ,取正方形ABCD 各邊的中點(diǎn)E,F,G,H, 作第2個(gè)正方形 EFGH,然后再取正方形EFGH各邊的中點(diǎn)I,J,K,L,作第3個(gè)正方形IJKL ,依此方法一直繼續(xù)下去. (1) 求從正方形ABCD 開始,連續(xù)10個(gè)正方形的面積之和;(2) 如果這個(gè)作圖過程可以一直繼續(xù)下去,那么所有這些正方形的面積之和將趨近于多少?分析:可以利用數(shù)列表示各正方形的面積,根據(jù)條件可知,這是一個(gè)等比數(shù)列。解:設(shè)正方形的面積為a_1,后續(xù)各正方形的面積依次為a_2, a_(3, ) 〖…,a〗_n,…,則a_1=25,由于第k+1個(gè)正方形的頂點(diǎn)分別是第k個(gè)正方形各邊的中點(diǎn),所以a_(k+1)=〖1/2 a〗_k,因此{(lán)a_n},是以25為首項(xiàng),1/2為公比的等比數(shù)列.設(shè){a_n}的前項(xiàng)和為S_n(1)S_10=(25×[1-(1/2)^10 ] )/("1 " -1/2)=50×[1-(1/2)^10 ]=25575/512所以,前10個(gè)正方形的面積之和為25575/512cm^2.(2)當(dāng)無限增大時(shí),無限趨近于所有正方形的面積和
新知探究前面我們研究了兩類變化率問題:一類是物理學(xué)中的問題,涉及平均速度和瞬時(shí)速度;另一類是幾何學(xué)中的問題,涉及割線斜率和切線斜率。這兩類問題來自不同的學(xué)科領(lǐng)域,但在解決問題時(shí),都采用了由“平均變化率”逼近“瞬時(shí)變化率”的思想方法;問題的答案也是一樣的表示形式。下面我們用上述思想方法研究更一般的問題。探究1: 對(duì)于函數(shù)y=f(x) ,設(shè)自變量x從x_0變化到x_0+ ?x ,相應(yīng)地,函數(shù)值y就從f(x_0)變化到f(〖x+x〗_0) 。這時(shí), x的變化量為?x,y的變化量為?y=f(x_0+?x)-f(x_0)我們把比值?y/?x,即?y/?x=(f(x_0+?x)-f(x_0)" " )/?x叫做函數(shù)從x_0到x_0+?x的平均變化率。1.導(dǎo)數(shù)的概念如果當(dāng)Δx→0時(shí),平均變化率ΔyΔx無限趨近于一個(gè)確定的值,即ΔyΔx有極限,則稱y=f (x)在x=x0處____,并把這個(gè)________叫做y=f (x)在x=x0處的導(dǎo)數(shù)(也稱為__________),記作f ′(x0)或________,即
二、典例解析例4. 用 10 000元購買某個(gè)理財(cái)產(chǎn)品一年.(1)若以月利率0.400%的復(fù)利計(jì)息,12個(gè)月能獲得多少利息(精確到1元)?(2)若以季度復(fù)利計(jì)息,存4個(gè)季度,則當(dāng)每季度利率為多少時(shí),按季結(jié)算的利息不少于按月結(jié)算的利息(精確到10^(-5))?分析:復(fù)利是指把前一期的利息與本金之和算作本金,再計(jì)算下一期的利息.所以若原始本金為a元,每期的利率為r ,則從第一期開始,各期的本利和a , a(1+r),a(1+r)^2…構(gòu)成等比數(shù)列.解:(1)設(shè)這筆錢存 n 個(gè)月以后的本利和組成一個(gè)數(shù)列{a_n },則{a_n }是等比數(shù)列,首項(xiàng)a_1=10^4 (1+0.400%),公比 q=1+0.400%,所以a_12=a_1 q^11 〖=10〗^4 (1+0.400%)^12≈10 490.7.所以,12個(gè)月后的利息為10 490.7-10^4≈491(元).解:(2)設(shè)季度利率為 r ,這筆錢存 n 個(gè)季度以后的本利和組成一個(gè)數(shù)列{b_n },則{b_n }也是一個(gè)等比數(shù)列,首項(xiàng) b_1=10^4 (1+r),公比為1+r,于是 b_4=10^4 (1+r)^4.