
1、 熱身日??谡Z練習(xí)。2、 預(yù)習(xí)引導(dǎo)學(xué)生使用第四課時(shí)學(xué)過的單詞和句型:What do you do on Saturdays? I often do my homework .并結(jié)合周末活動(dòng)的照片復(fù)習(xí)四會(huì)單詞和詞組,為本課時(shí)對(duì)話的學(xué)習(xí)做好準(zhǔn)備。3、 新課呈現(xiàn)Let’s try (1)在預(yù)習(xí)部分操練新詞組之后,教師可詢問學(xué)生的周末安排,然后出示本課時(shí)Let’s try部分的掛圖,讓學(xué)生根據(jù)掛圖說一說這些人物的周末活動(dòng),將聽與說相結(jié)合,適當(dāng)減緩Let’s try 聽力練習(xí)的難度。聽錄音,完成聽音圈圖的練習(xí)。Let’s talk (1)在部分聽覺感知新句型的基礎(chǔ)上,教師讓學(xué)生看掛圖聽錄音。(2)跟讀對(duì)話。Pair work 朗讀對(duì)話之后,讓學(xué)生結(jié)合自己的實(shí)際情況在同桌之間結(jié)對(duì)交流。Let’s check 播放錄音,讓學(xué)生按照錄音內(nèi)容做練習(xí)。第六課時(shí)教學(xué)設(shè)計(jì)教學(xué)內(nèi)容:B Read and write Group work C Task time教學(xué)目標(biāo):能聽懂、會(huì)說:并能在情景中運(yùn)用。

教讀句子:What’s your favourite food?(2)兩人小組用該句型編一小段對(duì)話進(jìn)行操練,同時(shí)也可引導(dǎo)學(xué)生用該句型編一小段對(duì)話進(jìn)行操練,同時(shí)也可引導(dǎo)學(xué)生用fruit and drink替換food.(3)聽錄音,讓學(xué)生跟讀對(duì)話。學(xué)生可用不同的食物單詞做替換回答問句。Pair work讓學(xué)生拿出已發(fā)的調(diào)查表格,用所學(xué)句型對(duì)不同學(xué)生進(jìn)行調(diào)查,并要求對(duì)方陳述原因。先組內(nèi)匯報(bào),再向全班匯報(bào),匯報(bào)時(shí)要說出:I like …… Mike likes…… We like……教師看哪一小組表現(xiàn)好,適當(dāng)給予獎(jiǎng)勵(lì)。Task time請(qǐng)學(xué)生拿出第一課時(shí)所做的謎語卡片,向全班展示。鞏固延伸:做配套練習(xí),讀對(duì)話給家長聽,熟記單詞第六課時(shí)教學(xué)設(shè)計(jì)教學(xué)目標(biāo)與要求:1、能夠聽、說、讀、寫本課時(shí)四會(huì)句子:What’s your favourite fruit?I like apples. They’re sweet. I don’t like grapes. They’re sour.并能在情景中正確運(yùn)用。能夠在Group work中使用該句型完成調(diào)查。2、能夠理解情景對(duì)話的含義并完成句子填空。3、能夠理解Pronunciation中字母組合的發(fā)音規(guī)則,讀出相關(guān)的單詞。

Step 3 (3b)First, tell the students when we talk about our future plans, we often use: I’m+verb+ing When we talk about what we must do, we use have to. Ask the students to fill in the blanks in 3b. The answers are: shopping, go to see, a test, I’m going, my family. Step 4 (3c)Let the students write an e-mail message to a friend. Say why you can’t visit next. Before the exercise, ask the students to give some possible answers and write them on the blackboard. So the students will feel easy to finish the writing exercise. After they finish it, Let them to correct it in groups first. Each group chooses theirs best one to read in front of the whole class. Step 5 ( planning a party )First read the conversation in the box together. Then ask the students to turn to page 88.Write down everything you have to do next week. Write in all the things you have to do . Ask the students to look at the list. Ask them “What day are you free?” This is when you can have your party. Step 6 (Self check 1 )Let the students to fill in the blanks with the words given. Change the forms of the words if possible. Then make their own sentences. The answers are: visit, playing, have to, study, comeStep 7 (Self check 2)Imagine you are Marie. Read the information and look at your schedule. Write replies to the invitation.

1. First, ... then, ... next, ... finally, ...首先,……然后,……接著,……最后,……這是英語中表達(dá)做某事的步驟的一種說法。如果步驟較多,還可以說:first-next-after that-later on-finally/at last通常你會(huì)聽到說英語國家的人在說 first, next, then, finally 和后面的內(nèi)容時(shí),他們會(huì)做一些停頓。這樣就能提前告訴聽者接下來講的是一系列的步驟。這一點(diǎn)在朗讀和聽力中應(yīng)特別注意。2. how many, how much均為疑問詞,同是“多少”,但用法不同。請(qǐng)看:how many修飾可數(shù)名詞復(fù)數(shù),how much修飾不可數(shù)名詞。但在用法上,同學(xué)們常犯如下錯(cuò)誤:1) [誤] How many are there bananas on the table?[正] How many bananas are there on the table?[析] how many, how much 中的many,much是形容詞,常修飾名詞作定語,故后面跟名詞。2) [誤]How much tea are there on the table?[正]How much tea is there on the table?[析] how much修飾不可數(shù)名詞時(shí),謂語動(dòng)詞用單數(shù)。how many與how much的區(qū)別可簡記為:前how many:問“多少”,復(fù)數(shù)名詞后面跑;how much問“多少”,不可數(shù)名詞單數(shù)好。前者答語用基數(shù)詞,后者答語用數(shù)量關(guān)系。

“Go for it!” is based on “Task-Based Language Teaching”. It adheres to “The authenticity principle”, “The form-function principle”, “The task dependency principle” and “The principle of learning by doing”. These principles all accord with the demands of curriculum focus.In and of Grade Seven (II), “Go for it!”, students have learned “The Simple Past Tense”. And it appears again in of Grade Eight (I). teaches students more about how to talk about events in the past. In addition, it gives affirmative and negative statements in the past tense, such as the sentence patterns “Did you see …?” “Were there …?” “Did you go …?” As the first part of Unit 8, Section A opens with a picture presenting the last school trip in the aquarium and continues with several step-by-step practice activities, which are all good for students to master “The Simple Past Tense”. Doing well in Section A will help students integrate the new target language with that in Section B. Thus, they can describe the events in the past freely and foster their own ability of reflecting and practicing. II. Teaching ObjectivesTeaching objective is the beginning and aim of teaching activities. According to the overall goal of the English elementary course--- improve students' synthetic ability of language application, which should be based on the development of students’ “Language knowledge”, “Language skills”, “Character building”, “Learning strategies” and “Cross-cultural awareness”. The teaching objectives are described as follows(I). Knowledge objectivesi. Master the simple past tense of regular and irregular verbsii. Recite the new words and expressions about the last school trip in the aquarium, including their pronunciation and intonation

一、 教學(xué)內(nèi)容Section A 1a----1c二、 教學(xué)目標(biāo)1.學(xué)習(xí)詞匯do the dishes, make the bed, take out the trash, fold the clothes, do the laundry, sweep the floor, clean the living room.2.句型 Could you please clean your room? Yes, sure.三、 教學(xué)準(zhǔn)備 學(xué)生預(yù)習(xí)本單元所有的詞匯多媒體課件 活動(dòng)表 獎(jiǎng)品四、 教學(xué)過程Pre-task1. Warming upEnjoy ourselves. Watch cartoon Cinderella. 看動(dòng)畫片段《灰姑娘》導(dǎo)如入本課話題和新詞匯“chores”美麗善良的鬼姑娘因繼母的嫉妒,每天得做所有的家務(wù)。片段的主題使學(xué)生聯(lián)想到本課的話題。2. learn new words and phrasesLook! What is she / he dong? 看圖學(xué)習(xí)動(dòng)詞詞組do chores, do the dishes, make the bed, take out the trash, fold the clothes, do the laundry, clean the living room.3. Guessing game.What is she doing ? 4. Pair work. 1a, Do you do these things at home? Write “Y” for “yes” and “N” for “no”.5. Listening . 1b , Peter’s chores or Mom’s chores?理解目標(biāo)語Could you please clean your room? Yes, sure.Write “M” for Mom’s chores, “P” for Peter’s chores in the chart.6. PairworkLook at the picture,Ask your partner to do the chores that you see. 7. Interview Who is the most able at home? 1) What chores do you do at home? How often do you do the chores? Work in four, interview each of the students in the group, fill in the chart.

Step Ⅶ Role play ( Work on 1b)1. First ask two students to read the dialogue to the class.Sa: How do you get to school?Sb: Well, I ride my bike to the subway station. Then I take the subway.2. Now work with a partner.Suppose you use two kinds of transportation to get to school \Hangzhou\Beijing... (bus, train, subway, walking, bike, etc.) Tell how you get there. You may use the phrases in 1a.3. Then ask different pairs of students to present their conversations to the class.Step ⅧListening1. Work on 2a(1) First ask students to read the list of information that Thomas wants to know.…where Nina lives.…h(huán)ow far from school she lives.…h(huán)ow long it takes to get to school.…h(huán)ow she gets to school.…what she thinks of the transportation.(2) Tell students what transportation and bus stop mean.bus stop 汽車站 transportation n. 運(yùn)送;運(yùn)輸Then tell students we'll hear a recording. Please put a checkmark in front of each thing that Thomas wants to know.(3) Now play the recording for students.( Have students pay attention to the sample answer.) (4) Then correct the answers.

Teaching goals : 1. Words & phrases: babysit ,get back , fishing , rent , think about , decide(on) , tourist etc. 2. How to talk about future plans . 3. 現(xiàn)在進(jìn)行時(shí)表示將來計(jì)劃或行動(dòng). 4. 特殊疑問句(where , when , how long引導(dǎo)) Important and difficult points : Drills :What are you doing for vacation ? I’m watching TV . When are you going ? I’m going … . How long are you staying ? We’re staying for five days . Teaching aids : cards and a tape ,a large wall calendar . Period 1 Teaching procedures : Step 1Leading in1. Free talk . 2. Put up the wall calendar . T: I’m staying home on Saturday (pointing to next Saturday ).Ss repeat . Ss: I’m staying home on Saturday . T: OK. Today we’ll learn how to talk about future plans. Step 2Pre-task SB Page 13 , 1a . 1. Look at the picture carefully and tell what you see in the picture . 2. Write the activities from the pictures in the box and add some more . 3. Practice reading . Step 3While-task1. Using the activities we write in 1a to make conversations .For example :What are you doing for vacation ? I’m visiting my uncle . 2. Pairwork .Practice in pairs . 3. 用第三人稱練習(xí)對(duì)話.

教學(xué)目標(biāo)1.知識(shí)目標(biāo):(1)學(xué)習(xí)What are you going to be when you grow up?/How are you going to do that?句式。(2)學(xué)會(huì)用英語描述有關(guān)職業(yè)的表達(dá)法。2.能力目標(biāo):(1)能夠談?wù)摓閷?shí)現(xiàn)理想所做出的打算和安排。(2)能夠談?wù)撐磥碜约号c他人理想的職業(yè)及原因。(3)能用英語描述課余時(shí)間的活動(dòng)安排,最終具備表達(dá)綜合信息的能力。3.情感目標(biāo):新學(xué)期到來之際,讓他們?cè)趯W(xué)習(xí)、體育、飲食、特長、讀書等方面制定計(jì)劃,教育學(xué)生合理安排自己的課外生活,思考自己的理想職業(yè)及適合自己的職業(yè)。教學(xué)重點(diǎn)、難點(diǎn)本單元的重點(diǎn)為“be going to”表將來,want to be, what,where, when,how引導(dǎo)的特殊疑問句。難點(diǎn)是語言目標(biāo)的實(shí)現(xiàn)。教材分析本單元以I am going to be a basketball player為話題,共設(shè)計(jì)了三部分的內(nèi)容:一、Section A該部分有4個(gè)模塊。第一模塊圍繞Do you think these jobs are interesting?這一話題展開思維(1a)、聽力(1b)、口語(1c)訓(xùn)練;

教學(xué)重點(diǎn)和難點(diǎn):運(yùn)用所掌握的語言描述,比較不同地點(diǎn)的特點(diǎn)。在練習(xí)中學(xué)習(xí)掌握英語比較級(jí)和最高級(jí)的用法。課前準(zhǔn)備分配小組,每組五至六人。通過上網(wǎng)或翻閱報(bào)刊雜志等方法,確定旅游線路,做出基本的旅游計(jì)劃。教學(xué)設(shè)計(jì):本節(jié)課流程圖 學(xué)法指導(dǎo):1.由于這是一堂新課,在教學(xué)中應(yīng)注意面向全體,發(fā)揮學(xué)生的主體性,引導(dǎo)學(xué)生積極參與,激發(fā)學(xué)生的求知欲和學(xué)習(xí)積極性,指導(dǎo)學(xué)生積極思維,主動(dòng)獲取知識(shí),養(yǎng)成良好的學(xué)習(xí)方法。逐步學(xué)會(huì)獨(dú)立解決問題??傊M可能調(diào)動(dòng)學(xué)生的非智力因素促進(jìn)智力因素的發(fā)展。教法選擇:1.電化教學(xué)法2.課堂討論法3.任務(wù)型教學(xué)法采用這些方法的目的是為了充分調(diào)動(dòng)學(xué)生的學(xué)習(xí)積極性,使學(xué)生變被動(dòng)學(xué)習(xí)為主動(dòng)學(xué)習(xí)。通過電腦形象的演示,加強(qiáng)印象,提高興趣,突破難點(diǎn),提高教學(xué)效率,進(jìn)而增大教學(xué)的容量和信息量。充分體現(xiàn)教師為主導(dǎo),學(xué)生為主體的教學(xué)原則。

She shouldn’t go to the party tonight.Step7. TaskT: You know, there are lots of problems in our life. If you are a doctor, please tell us how to solve the problem. I will divide you into 9 groups. Please work in groups. And then choose one of you to report your ideas.The following are the problems:I have a toothache.I am hungry. I have a sore throat.I am stressed out. I have a sore back.I am tired. I can’t sleep.I have a cold. I have a headache.Report: If you have a headache, you should go to bed early. You should see the doctor. You should eat some medicine. You shouldn’t wash your face with cold water.You shouldn’t sleep late.You shouldn’t swim.…..T encourages the students to give advice as much as possible.Homework:1. Chose one of the problems, and write down your advice2. Copy the new words這一步是用于熱身的,同時(shí)也可以讓他們復(fù)習(xí)一部分的表示人體部位的單詞,擴(kuò)充知識(shí).學(xué)習(xí)語言的過程也是一個(gè)不斷積累的過程,復(fù)習(xí)舊知識(shí),增添新知識(shí).通過小游戲,強(qiáng)化學(xué)生對(duì)Does she/he have…這個(gè)句子的運(yùn)用能力.通過復(fù)習(xí),自然的引到下面新知識(shí)的學(xué)習(xí)。充分利用表格,由句子到對(duì)話,再到文章,讓學(xué)生循序漸進(jìn). 提高學(xué)生的綜合語言運(yùn)用能力,運(yùn)用以前學(xué)過的知識(shí)來解決身邊的問題.Period 5 (Section B 3a—3c, selfcheck)教學(xué)內(nèi)容與分析:

1 交通工具的比較此活動(dòng)為小組活動(dòng)。學(xué)生通過討論找出到達(dá)某一城市可乘坐的各種交通工具,并選擇最佳出行方式。Teacher:We’re going to Shanghai. How many ways can we use to get there? Yes, there are four ways: by bus, by plane, by train, by ship. Please discuss how you are going to get there.操作建議:(1)學(xué)生以小組為單位展開活動(dòng),談?wù)摫窘M所選擇的交通工具。(2)各組選代表向全班匯報(bào),闡述本組所選擇的交通工具的利和弊。完成任務(wù)所需要的語言結(jié)構(gòu):We can go there by ship. It’s more comfortable and cheaper than any other transportation.We can go there by bus. It’s cheaper but it takes longer time.2 哪個(gè)城市更合適?此活動(dòng)具有挑戰(zhàn)性。假設(shè)中國要舉行2014年世界杯足球賽,分別從歷史,人文,天氣等方面對(duì)各城市(北京,大連,上海,昆明)進(jìn)行比較,選擇最佳舉辦城市。T: Imagine China is holding the 2014 FIFA World Cup. Which city do you think is the best for the World Cup, Beijing, Dalian, Shanghai or Kunming? Let’s work in groups. If you choose Beijing, please join the Team Red. If you chose Dalian, please join the Team White. If you choose Shanghai, please join the Team Blue. If you choose Kunming, please join the Team Green. Please show us its advantages. Then let’s see which team will win.

解析:此題作為一道開放型題,分類的方法非常多,只要能說明分類的理由即可.但要注意:按某一標(biāo)準(zhǔn)分類時(shí),要做到不重不漏,分類標(biāo)準(zhǔn)不同時(shí),分類的結(jié)果也就不盡相同.解:本題答案不唯一,如按柱體、錐體、球體分類:(2)(3)(5)和(6)都是柱體,(4)(7)是錐體,(1)是球體.方法總結(jié):生活中常見幾何體有兩種分類:一種按柱體、錐體、球體分類;一種按平面和曲面分類.探究點(diǎn)二:幾何體的形成筆尖畫線可以理解為點(diǎn)動(dòng)成線.使用數(shù)學(xué)知識(shí)解釋下列生活中的現(xiàn)象:(1)流星劃破夜空,留下美麗的弧線;(2)一條拉直的細(xì)線切開了一塊豆腐;(3)把一枚硬幣立在桌面上用力一轉(zhuǎn),形成一個(gè)球.解析:解釋現(xiàn)象關(guān)鍵是看其屬于什么運(yùn)動(dòng).解:(1)點(diǎn)動(dòng)成線;(2)線動(dòng)成面;(3)面動(dòng)成體.方法總結(jié):生活中的很多現(xiàn)象都可以用數(shù)學(xué)知識(shí)來解釋,關(guān)鍵是要找到生活實(shí)例與數(shù)學(xué)知識(shí)的連接點(diǎn),如第(1)題可將流星看作一個(gè)點(diǎn),則“點(diǎn)動(dòng)成線”.如圖所示,將平面圖形繞軸旋轉(zhuǎn)一周,得到的幾何體是()

1、 如圖4-25,將一個(gè)圓分成三個(gè)大小相同的扇形,你能算出它們的圓心角的度數(shù)嗎?你知道每個(gè)扇形的面積和整個(gè)圓的面積的關(guān)系嗎?與同伴進(jìn)行交流2、 畫一個(gè)半徑是2cm的圓,并在其中畫一個(gè)圓心為60º的扇形,你會(huì)計(jì)算這個(gè)扇形的面積嗎?與同伴交流。教師對(duì)答案進(jìn)行匯總,講解本題解題思路:1、 因?yàn)橐粋€(gè)圓被分成了大小相同的扇形,所以每個(gè)扇形的圓心角相同,又因?yàn)閳A周角是360º,所以每個(gè)扇形的圓心角是360º÷3=120º,每個(gè)扇形的面積為整個(gè)圓的面積的三分之一。2、 先求出這個(gè)圓的面積S=πR²=4π,60÷360=1/6扇形面積=4π×1/6=2π/3【設(shè)計(jì)意圖】運(yùn)用小組合作交流的方式,既培養(yǎng)了學(xué)生的合作意識(shí)和能力,又達(dá)到了互幫互助以弱帶強(qiáng)的目的,使學(xué)習(xí)比較吃力的同學(xué)也能參與到學(xué)習(xí)中來,體現(xiàn)了學(xué)生是學(xué)習(xí)的主體。

1.了解“兩點(diǎn)之間,線段最短”.2.能借助尺、規(guī)等工具比較兩條線段的大小,能用圓規(guī)作一條線段等于已知線段.3.了解線段的中點(diǎn)及線段的和、差、倍、分的意義,并能根據(jù)條件求出線段的長.一、情境導(dǎo)入愛護(hù)花草樹木是我們每個(gè)人都應(yīng)具備的優(yōu)秀品質(zhì).從教學(xué)樓到圖書館,總有少數(shù)同學(xué)不走人行道而橫穿草坪(如圖),同學(xué)們,你覺得這樣做對(duì)嗎?為了解釋這種現(xiàn)象,學(xué)習(xí)了下面的知識(shí),你就會(huì)知道.二、合作探究探究點(diǎn)一:線段長度的計(jì)算【類型一】 根據(jù)線段的中點(diǎn)求線段的長如圖,若線段AB=20cm,點(diǎn)C是線段AB上一點(diǎn),M、N分別是線段AC、BC的中點(diǎn).(1)求線段MN的長;(2)根據(jù)(1)中的計(jì)算過程和結(jié)果,設(shè)AB=a,其它條件不變,你能猜出MN的長度嗎?請(qǐng)用簡潔的話表達(dá)你發(fā)現(xiàn)的規(guī)律.

教學(xué)反思: 1.本課時(shí)設(shè)計(jì)的主導(dǎo)思想是:將數(shù)形結(jié)合的思想滲透給學(xué)生,使學(xué)生對(duì)數(shù)與形有一個(gè)初步的認(rèn)識(shí).為將來的學(xué)習(xí)打下基礎(chǔ),這節(jié)課是一堂起始課,它為學(xué)生的思維開拓了一個(gè)新的天地.在傳統(tǒng)的教學(xué)安排中,這節(jié)課的地位沒有提到一定的高度,只是交給學(xué)生比較線段的方法,沒有從數(shù)形結(jié)合的高度去認(rèn)識(shí).實(shí)際上這節(jié)課大有可講,可以挖掘出較深的內(nèi)容.在教知識(shí)的同時(shí),交給學(xué)生一種很重要的數(shù)學(xué)思想.這一點(diǎn)不容忽視,在日常的教學(xué)中要時(shí)時(shí)注意.2.學(xué)生在小學(xué)時(shí)只會(huì)用圓規(guī)畫圓,不會(huì)用圓規(guī)去度量線段的大小以及截取線段,通過這節(jié)課,學(xué)生對(duì)圓規(guī)的用法有一個(gè)新的認(rèn)識(shí).3.在課堂練習(xí)中安排了度量一些三角形的邊的長度,目的是想通過度量使學(xué)生對(duì)“兩點(diǎn)之間線段最短”這一結(jié)論有一個(gè)感性的認(rèn)識(shí),并為下面的教學(xué)做一個(gè)鋪墊.

1.經(jīng)歷從不同方向觀察物體的活動(dòng)過程,發(fā)展空間觀念.2.在觀察的過程中,初步體會(huì)從不同方向觀察同一物體可能看到不同的形狀.3.能識(shí)別從三個(gè)方向看到的簡單物體的形狀,會(huì)畫立方體及簡單組合體從三個(gè)方向看到的形狀,并能根據(jù)看到的形狀描述基本幾何體或?qū)嵨镌停弧⑶榫硨?dǎo)入觀察圖中不同方向拍攝的廬山美景.你能從蘇東坡《題西林壁》詩句:“橫看成嶺側(cè)成峰,遠(yuǎn)近高低各不同.不識(shí)廬山真面目,只緣身在此山中.”體驗(yàn)出其中的意境嗎?你能挖掘出其中蘊(yùn)含的數(shù)學(xué)道理嗎?讓我們一起探索新知吧!二、合作探究探究點(diǎn)一:從不同的方向看物體如圖所示的幾何體是由一些小正方體組合而成的,從上面看到的平面圖形是()解析:這個(gè)幾何體從上面看,共有2行,第一行能看到3個(gè)小正方形,第二行能看到2個(gè)小正方形.故選D.

【教學(xué)目標(biāo)】1.經(jīng)歷從不同方向觀察物體的活動(dòng)過程,發(fā)展空間觀念;能在與他人交流的過程中,合理清晰地表達(dá)自己的思維過程.2.在觀察的過程中,初步體會(huì)從不同方向觀察同一物體可能看到不同的圖形.3.能識(shí)別簡單物體的三視圖,會(huì)畫立方體及其簡單組合體的三視圖.【基礎(chǔ)知識(shí)精講】1.主視圖、左視圖、俯視圖的定義從不同方向觀察同一物體,從正面看到的圖叫主視圖,從左面看到的圖叫左視圖,從上面看到的圖叫做俯視圖.2.幾種幾何體的三視圖(1)正方體:三視圖都是正方形.圓錐的主視圖、左視圖都是三角形,而俯視圖的圖中有一個(gè)點(diǎn)表示圓錐的頂點(diǎn),因?yàn)閺纳贤驴磮A錐時(shí)先看到圓錐的頂點(diǎn),再看到底面的圓.3.如何畫三視圖 當(dāng)用若干個(gè)小正方體搭成新的幾何體,如何畫這個(gè)新的幾何體的三視圖?

(1)請(qǐng)你用代數(shù)式表示水渠的橫斷面面積;(2)計(jì)算當(dāng)a=3,b=1時(shí),水渠的橫斷面面積.解析:(1)根據(jù)梯形面積=12(上底+下底)×高,即可用含有a、b的代數(shù)式表示水渠橫斷面面積;(2)把a(bǔ)=3、b=1帶入到(1)中求出的代數(shù)式中,其結(jié)果即為水渠的橫斷面面積.解:(1)∵梯形面積=12(上底+下底)×高,∴水渠的橫斷面面積為:12(a+b)b(m2);(2)當(dāng)a=3,b=1時(shí)水渠的橫斷面面積為12(3+1)×1=2(m2).方法總結(jié):解答本題時(shí)需搞清下列幾個(gè)問題:(1)題目中給出的是什么圖形?(2)這種圖形的面積公式是什么?(3)根據(jù)公式求圖形的面積需要知道哪幾個(gè)量?(4)這些量是否已知或能求出?搞清楚了這些問題,求解就水到渠成.三、板書設(shè)計(jì)教學(xué)過程中,應(yīng)通過活動(dòng)使學(xué)生感知代數(shù)式運(yùn)算在判斷和推理上的意義,增強(qiáng)學(xué)生學(xué)習(xí)數(shù)學(xué)的興趣,培養(yǎng)學(xué)生積極的情感和態(tài)度,為進(jìn)一步學(xué)習(xí)奠定堅(jiān)實(shí)的基礎(chǔ).

解 由題意可得,今年的年產(chǎn)值為a·(1+10%) 億元,于是明年的年產(chǎn)值為a·(1+10%)·(1+10%)= 1.21a(億元).若去年的年產(chǎn)值為2億元,則明年的年產(chǎn)值為1.21a =1.21×2 = 2.42(億元).答:該企業(yè)明年的年產(chǎn)值將能達(dá)到1.21a億元.由去年的年產(chǎn)值是2億元,可以預(yù)計(jì)明年的年產(chǎn)值是2.42億元.例3 當(dāng)x=-3時(shí),多項(xiàng)式mx3+nx-81的值是10,當(dāng)x = 3時(shí),求該代數(shù)式的值.解 當(dāng)x=-3時(shí),多項(xiàng)式mx3+nx-81=-27m-3n-81, 此時(shí)-27m-3n-81=10, 所以27m+3n=-91.則當(dāng)x=3,mx3+nx-81 =( 27m+3n )-81=-91-81=-172.注:本題采用了一種重要的數(shù)學(xué)思想——“整體思想”.即是考慮問題時(shí)不是著眼于他的局部特征,而是把注意力和著眼點(diǎn)放在問題的整體結(jié)構(gòu)上,把一些彼此獨(dú)立,但實(shí)質(zhì)上又相互緊密聯(lián)系著的量作為整體來處理的思想方法.
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