1. Get basic information about Eric; read deeply to understand the history and development of the virtual choir.2. Understand what the function of the virtual choir is and how to make a virtual choir.3. Understand the meaning of some languages in the context of the text through question guidance, such as “Many people do not have close friends or contacts who have the same interest in music.” and so on.Step 1 Leading-in1. Answer the following questions.Q1:Do you know the Apps like Tik Tok and Quick Hand?Q2: Do you want to make a Tik Tok video or a Quick Hand video?2. Play a Tik Tok video Step 2: Understanding the title Q1:What does the title mean ?Q2: Is the article a narration or exposition? Why? Q3: Can you change the title ? If you can, what is the title?Step 3: Scanning the whole text and getting the basic information1. Answer the following questions.Q1:Who came up with the idea for a virtual choir?Q2: Where did Eric studied the musical composition?Q3: What is his song?2. Find the main idea of each paragraph3. Deal with some new words.Step 4: Reading carefully to get detailed informationPara 1 How to make a virtual choir1. PreparationA. tools: a virtual camera; an Internet connectionB. hero/heroin: friends or some individuals who have the same interests2. Process
The Internet celebrity Gao Yifeng. Years ago, he owned 5 companies and the staffs over 1,000, but during the economy crisis, he became nothing but debt. He was so worried that his hair became white overnight. There was a time when he wanted to killed himself. But after listening to the song Start Over by Liu Huan, he decided to cheer himself up. He started a steamed bun shop and gradually became a national chain shops. Now he became successful again.Walter Haddon said, “Music is the medicine of a troubled mind.” Music contains such a pleasant and inspiring force. Music gave him courage and bravery. When he listened to the song, it made his spirit fly like a kite in the wind. Music gave him strength and brought him relief. It was the rock I leant on to become strong and to get through those hard times. I hope none of us have to go through the same kind of suffering that he did. At the same time, we all go through various periods when we feel sad or alone. During those times, music can help us in the same way that it helped him. I hope we all will somehow begin to treasure music and make it a part of our life. Thank you for your listening !5.Revise your writing each other.Does he/she explain how music has changed his/her/someone else’s life?Are some of the rhetorical devices included and used properly ?Does he/she talk about how music makes him/her/someone feel?Is the first word in each sentences capitalised?Does he/she use correct punctuation ?
Activity 41. Students complete the task of activity 4, then teachers and students check the answers. 2. The teacher organized the students to work together and asked them to use the tables and mind maps sorted out before to retold the important choices in Lin Qiaozhi's life and their resultsStep 5 Language points1. The teacher asks the students to read the text carefully, find out the core words and long and difficult sentences in the text and draw lines, understand the use of vocabulary, and analyze the structure of long and difficult sentences. 2. The teacher explains and summarizes the usage of core vocabulary and asks the students to take notes. 3. The teacher analyzes and explains the long and difficult sentences that the students don't understand, so that the students can understand them better. Step 6 Homework1. Read the text again, in-depth understanding of the text; 2. Master the use of core vocabulary and understand the long and difficult sentences. 3. Complete relevant exercises in the guide plan. 1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生是否理解和掌握閱讀文本中的新詞匯的意義與用法;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否結(jié)合文本特點總結(jié)林巧稚的人生原則和人格品質(zhì)特征;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否針對人生抉擇發(fā)表自己的看法;能否全面地、客觀地、理性地看待問題,進而對道德和人性有更加深入的思考和理解。
The joke set her crying.這個玩笑使她哭起來。Step 5 ReadingActivity 31. Students read the small text in activity 3. The teacher provides several small questions to check whether students understand the content of the text and the ideographic function of the -ing form in the text.*Where are those people?*Why did Dr Bethune come to China?*How did he help the Chinese people during the war?*What did Chairman Mao Zedong say about him?2. Ss try to rewrite some sentences using the -ing form. Then check the answers. When checking the answers, the teacher can ask different students to read the rewritten sentences and give comments.Answers:1. he became very interested in medicine, deciding to become a doctor.2. …after hearing that many people were dying in the war.3. Helping to organise hospitals, he taught doctors and nurses, and showed people how to give first aid./ He helped to organise hospitals, teaching doctors and nurses, and showing people how to give first aid.4. …praising Dr Bethune as a hero to be remembered in China.Step 6 PracticeActivity 4Students complete grammar activities 2 and 3 on page 69 of the workbook.Step 6 Homework1. Understand and master the functions and usage of the -ing form;2. Finish the other exercises in Using structures.1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生是否理解和掌握動詞-ing形式作賓語補足語語和狀語語的功能和意義;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否正確使用動詞-ing形式描述人物的行為、動作及其經(jīng)歷;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否獨立完成練習(xí)冊和導(dǎo)學(xué)案中的相關(guān)練習(xí)。
3.Teachers ask different groups to report the answers to the questions and ask them to try different sentence patterns.The teacher added some sentence patterns for students to refer to when writing.Step 4 Writing taskActivity 51.Write the first draft.Students first review the evaluation criteria in activity 5, and then independently complete the draft according to the outline of activity 4, the answers to the questions listed in the group discussion and report, and the reference sentence pattern.2.Change partners.The teacher guides the students to evaluate their partner's composition according to the checklist of activity 5 and proposes Suggestions for modification.3.Finalize the draft.Based on the peer evaluation, students revise their own compositions and determine the final draft.Finally, through group recommendation, the teacher selects excellent compositions for projection display or reading aloud in class, and gives comments and Suggestions.Step 5 Showing writingActivity 5T call some Ss to share their writing.Step 6 Homework1. Read the passage in this section to better understand the passage.2. Carefully understand the hierarchical structure of the article, and deeply understand the plot of the story according to the causes, process and results;3. Independently complete the relevant exercises in the guide plan.1、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生是否理解和掌握閱讀文本中的新詞匯的意義與用法;2、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否通過人物言行的對比分析道德故事的深層內(nèi)涵;3、通過本節(jié)內(nèi)容學(xué)習(xí),學(xué)生能否根據(jù)故事的起因、經(jīng)過和結(jié)果來深入理解故事的情節(jié),從而了解文章的層次結(jié)構(gòu);4、結(jié)合現(xiàn)實生活案例發(fā)表自己的見解和看法,寫一篇觀點明確、層次分明的故事評論。
Listening and Speaking introduces the topic of “Take part in a youth project”. The listening text is an interview about "sharing views on historical sites". Through listening to a dialogue between Chinese and foreign students on the way to the Confucius Temple, students can understand their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts, so as to realize and think about the profound influence of Confucius and his thoughts on Chinese historical tradition. At the same time, the dialogue naturally integrates English idioms and mentions Shakespeare, the British playwright, so as to provide language materials and context for students to understand English idioms and related cultural allusions, as well as to compare Chinese and foreign cultures, which is helpful for students to understand and express the language such as history, tradition, culture and custom significant impact.Text analysis: listening text is a dialogue between a British student and a Chinese student when he goes to the Confucius Temple. When William, a British student, visited the Confucius Temple, he asked Xiao Kong, a Chinese student, for directions. Xiao Kong was just going to the Confucius Temple to meet with the members of the research group, so they went together and exchanged their views on the Confucius Temple, Confucius, Confucius' descendants and Confucius' educational thoughts. From the perspective of foreign tourists, this paper describes their thoughts on Confucius, the great son of Confucius, who had a profound impact on Chinese history and cultural tradition, and his education.Listening and Talking introduces a visit to a historic tourist destination. Tourism is a common way to understand a country's history, culture, and customs and so on. Students listen to the dialogue between Xiao Yan, a youth hostel Usher, and Paul, a backpacker, to learn about Pingyao's famous historical and cultural attractions and Paul's travel experience and experience as a foreign tourist.
Step 1 Lead inThere are many interest of places in the UK. What do you know ?The Big Ben the London Tower the Thames RiverStep 2 Before reading---analyze the titleBeautiful Ireland and its traditionWe know that the article mainly tells about the beauty and traditions of Ireland. Step 3 While reading---Task 1Read the text and answer the following questions.Q1: What makes the Irish countryside exciting and inspiring?Its beauty and how it offers something for all the scenes.Q2: What are the best ways to experience some Irish traditions and cultures?By stopping by a village pub and relaxing with a drink and traditional meal while listening to music and watching dancingQ3: What is the meaning of “breathe in the sweet scent of fresh flowers while birds greet the new day with their morning song ?”It means to not just smell but also breathe in the smell of fresh flowers early in the morning as the birds sing their first song of the new day.Q4: What are the best ways to experience Chinese traditions and customs ?By travelling to different places and using all your senses to experience everything and by interacting with local people.Step 4 While reading---Task 2Analyze the descriptive paragraph1. Identify and underline the paragraph’s introductory sentence and the ending sentence.Introductory sentence: Ireland’s beautiful countryside has always had a great influence on its people and traditions.Ending sentence: And if you introduce yourself to a friendly face, you are more than likely to experience local culture and customs first-hand.2. The paragraph talks about different senses in different places. Write the senses and places in the order that they appear.
This lesson is about music. Students can classify the types of music through the instruments and its sound and can talk about their preferences about music, even join some activities and play a role in them according to their musical talents. On the basis, they are guided to use the languages to express their preferences and some plosive sounds and their rules.1. Classify the music types through the instruments and its sound.2. Listen and understand what the speakers’ preferences are and the reasons; talk about their own preferences and give their own reasons, using these sentences: “What kind of music do you like? And why? “ “Because it makes/gives me energy/peaceful.../touches my heart...”.3. Learn some plosives and the rules.4. Join some activities and play a role in them according to the talents. 1. Listen and understand what the speakers’ preferences are and the reasons;2. talk about their own preferences and give their own reasons, using these sentences: “What kind of music do you like? And why? “ “Because it makes/gives me energy/peaceful.../touches my heart...”.3. Learn some plosives and incomplete plosives and its rules.Step 1 Lead inPoint at the pictures on P50 and ask Q1: What are the people doing in the pictures below?Q2: What kind of music they are?Then play the MP3s one by oneStep 2 ListeningTask 1: A reporter from the school newspaper is interviewing students about music. Listen to the interviews. Draw lines between the words to make complete sentences. Some words will not be used.
本板塊的活動主題是“談?wù)摴?jié)日活動”(Talk about festival activities),主要是從貼近學(xué)生日常生活的角度來切入“節(jié)日”主題。學(xué)生會聽到發(fā)生在三個國家不同節(jié)日場景下的簡短對話,對話中的人們正在參與或?qū)⒁H歷不同的慶祝活動。隨著全球化的進程加速,國際交流日益頻繁,無論是國人走出國門還是外國友人訪問中國,都已成為司空見慣的事情。因此,該板塊所選取的三個典型節(jié)日場景都是屬于跨文化交際語境,不僅每組對話中的人物來自不同的文化背景,對話者的身份和關(guān)系也不盡相同。1. Master the new words related to holiday: the lantern, Carnival, costume, dress(sb)up, march, congratulation, congratulate, riddle, ceremony, samba, make - up, after all. 2. To understand the origin of major world festivals and the activities held to celebrate them and the significance of these activities;3. Improve listening comprehension and oral expression of the topic by listening and talking about traditional festivals around the world;4. Improve my understanding of the topic by watching pictures and videos about different traditional festivals around the world;5. Review the common assimilation phenomenon in English phonetics, can distinguish the assimilated phonemes in the natural language flow, and consciously use the assimilation skill in oral expression. Importance:1. Guide students to pay attention to the attitude of the speaker in the process of listening, and identify the relationship between the characters;2. Inspire students to use topic words to describe the festival activities based on their background knowledge. Difficulties:In the process of listening to the correct understanding of the speaker's attitude, accurately identify the relationship between the characters.
Activity 81.Grasp the main idea of the listening.Listen to the tape and answer the following questions:Who are the two speakers in the listening? What is their relationship?What is the main idea of the first part of the listening? How about the second part?2.Complete the passage.Ask the students to quickly review the summaries of the two listening materials in activity 2. Then play the recording for the second time.Ask them to complete the passage and fill in the blanks.3.Play the recording again and ask the students to use the structure diagram to comb the information structure in the listening.(While listening, take notes. Capture key information quickly and accurately.)Step 8 Talking Activity 91.Focus on the listening text.Listen to the students and listen to the tape. Let them understand the attitudes of Wu Yue and Justin in the conversation.How does Wu Yue feel about Chinese minority cultures?What does Justin think of the Miao and Dong cultures?How do you know that?2.learn functional items that express concerns.Ask students to focus on the expressions listed in activity. 3.And try to analyze the meaning they convey, including praise (Super!).Agree (Exactly!)"(You're kidding.!)Tell me more about it. Tell me more about it.For example, "Yeah Sure." "Definitely!" "Certainly!" "No kidding!" "No wonder!" and so on.4.Ask the students to have conversations in small groups, acting as Jsim and his friends.Justin shares his travels in Guizhou with friends and his thoughts;Justin's friends should give appropriate feedback, express their interest in relevant information, and ask for information when necessary.In order to enrich the dialogue, teachers can expand and supplement the introduction of Miao, dong, Lusheng and Dong Dage.After the group practice, the teacher can choose several groups of students to show, and let the rest of the students listen carefully, after listening to the best performance of the group, and give at least two reasons.
請回答:根據(jù)上述材料,概述第二次工業(yè)革命興起的主要原因?!紖⒖即鸢浮舰僬紊希Y本主義制度在世界范圍內(nèi)的確立,為第二次工業(yè)革命提供了政權(quán)保障。②市場上,世界市場進一步拓展,推動生產(chǎn)進步發(fā)展。③科技上,19世紀自然科學(xué)的飛速發(fā)展與重大突破。④勞動力上,擁有更多、素質(zhì)更好的自由勞動力。⑤經(jīng)濟上,擁有更加雄厚的資本。探索攻關(guān)二:第二次工業(yè)革命與壟斷組織的出現(xiàn)的關(guān)系材料一第二次工業(yè)革命產(chǎn)生的新興工業(yè)部門,在廠房、設(shè)備、技術(shù)要求和產(chǎn)品結(jié)構(gòu)的復(fù)雜性等方面,都對生產(chǎn)組織提出了新的要求。這是過去的獨家企業(yè)無法滿足的,而且一般沒有足夠的資金?!谑牵匈Y金的合股公司迅速增加起來,起大型企業(yè)壟斷組織也就應(yīng)運而生。
反思感悟用基底表示空間向量的解題策略1.空間中,任一向量都可以用一個基底表示,且只要基底確定,則表示形式是唯一的.2.用基底表示空間向量時,一般要結(jié)合圖形,運用向量加法、減法的平行四邊形法則、三角形法則,以及數(shù)乘向量的運算法則,逐步向基向量過渡,直至全部用基向量表示.3.在空間幾何體中選擇基底時,通常選取公共起點最集中的向量或關(guān)系最明確的向量作為基底,例如,在正方體、長方體、平行六面體、四面體中,一般選用從同一頂點出發(fā)的三條棱所對應(yīng)的向量作為基底.例2.在棱長為2的正方體ABCD-A1B1C1D1中,E,F分別是DD1,BD的中點,點G在棱CD上,且CG=1/3 CD(1)證明:EF⊥B1C;(2)求EF與C1G所成角的余弦值.思路分析選擇一個空間基底,將(EF) ?,(B_1 C) ?,(C_1 G) ?用基向量表示.(1)證明(EF) ?·(B_1 C) ?=0即可;(2)求(EF) ?與(C_1 G) ?夾角的余弦值即可.(1)證明:設(shè)(DA) ?=i,(DC) ?=j,(DD_1 ) ?=k,則{i,j,k}構(gòu)成空間的一個正交基底.
二、課堂教學(xué)(課前由科代表發(fā)回預(yù)習(xí)學(xué)案)1、教師根據(jù)預(yù)習(xí)學(xué)案檢查結(jié)果提出問題(用多媒體展示),引導(dǎo)全班討論(重點討論:①、為什么動能的表達式一定是 mV2 ?你如何得出這個結(jié)論?②、力在一個過程中對物體所做的功,和物體在這個過程中動能的變化量有什么關(guān)系?你如何得出這個結(jié)論?這個做功的力和F=ma中的力F有什么關(guān)系)。有困難的小組應(yīng)及時問老師。老師在這個過程中巡視指導(dǎo)。2、學(xué)生自主閱讀課文“7 動能和動能定理”中的“動能的表達式”,然后完成如下練習(xí)(教師在此過程中巡視指導(dǎo)):2.1嘗試推出動能的表達式(鼓勵會推導(dǎo)的同學(xué)積極上臺板演,老師引導(dǎo)討論)。2.2寫出動能的小結(jié)(認真閱讀教材p66倒數(shù)第二段、第三段,結(jié)合你推導(dǎo)動能表達式的過程,認真思考后四人一組討論:①、動能是矢量還是標量?②、動能的單位是什么?③、你認為應(yīng)從哪幾方面來理解動能?)
1. 課前觀看視頻《物理學(xué)與人類文明》2. 分組討論,派代表發(fā)言,談學(xué)習(xí)感受。主要是物理的地位,物理的學(xué)習(xí)方法。3. 高中物理與初中物理在內(nèi)容和方法上的區(qū)別高中物理除了現(xiàn)象、概念和規(guī)律之外還應(yīng)該關(guān)注研究問題的方法,學(xué)會從先想到抽象,從定性到定量研究問題,學(xué)會用數(shù)學(xué)方法解決物理問題,學(xué)會實驗探究,學(xué)會獨立分析問題解決問題的思維習(xí)慣。4. 高中物理學(xué)習(xí)的基本要求高中物理學(xué)習(xí)應(yīng)該“重視實驗,勤于思考”和“經(jīng)歷過程,體驗方法”。高中物理學(xué)習(xí)與初中物理學(xué)習(xí)雖然有一定區(qū)別,但也不是孤立的,要繼續(xù)堅持初中物理學(xué)習(xí)中積累的學(xué)習(xí)方法和體會,重視從正反兩個方面加以總結(jié)和提煉,做到:(1) 認真閱讀,學(xué)會自學(xué)要學(xué)好物理,就要認真閱讀課本。閱讀課本是要抓住關(guān)鍵詞語,弄清語句間的邏輯順序和因果關(guān)系,領(lǐng)會文章段落所表達的物理內(nèi)容,掌握課本敘述物理問題的表達方法。
八、物理學(xué)的基礎(chǔ)地位及物理學(xué)對人類文明、社會進步的影響。(1) 情景一:磁懸浮實驗:找兩個空心的圓柱片磁鐵,同名磁極相對,穿在同一根竹筷上,用手壓下上面的磁鐵,松手觀察它的運動情況。問題1:上面的磁鐵為什么會跳起來,為什么會懸浮在下面的磁鐵上方?問題2:根據(jù)這個實驗,你會想到那一種交通工具?總結(jié):人們就是從磁懸浮現(xiàn)象中得到啟發(fā),進行磁懸浮列車的研究和制造的,這說明物理學(xué)在推動社會進步、人類文明方面起到推動作用。(2) 情景二:感應(yīng)起電和火花放電實驗:用感應(yīng)起電機或感應(yīng)圈產(chǎn)生火花放電,讓學(xué)生觀察現(xiàn)象,聞氣味,然后聯(lián)想生活實例。還可以用一張紙試著擋住放電的弧光,最好能引燃紙張,說明雷擊引起火災(zāi)的現(xiàn)象。問題1:你看、聽到了什么現(xiàn)象?問題2:根據(jù)這個實驗,你會想到那一種自然現(xiàn)象?問題3:放電發(fā)生在什么地方?為什么建筑物上方都有尖尖的設(shè)置,是干什么用的?問題4:你聞到什么氣味了嗎?
1、第一,材料一和材料二的選舉方式有什么異同?(1)相同點:①都采用了演講和答辯等形式,都帶有競選的性質(zhì);②都采用無記名、直接選舉的方式進行投票選舉;③都屬于差額選舉。(2)不同點:①材料一是對村主任進行的正式選舉,結(jié)果是直接產(chǎn)生村主任,材料二是對鎮(zhèn)長候選人進行的選舉,結(jié)果只是確定鎮(zhèn)長候選人,鎮(zhèn)長人選還有待進行正式選舉;②材料一是全體村民都參加選舉,材料二是各戶派代表參加選舉;③材料二比材料一更強調(diào)競選的方式。第二,你還知道哪些選舉方式?除了直接選舉外,還有間接選舉、等額選舉、差額選舉等。第三,你能對這幾種選舉方式的意義和效果,作出自己的評估嗎?這是學(xué)習(xí)中要探究的問題,這里不一定能回答出來,等到學(xué)完本框內(nèi)容后,可以得出比較明確的答案。第四,材料三給了你什么啟示?這個問題不要求統(tǒng)一的答案,能講出一兩點即可。提示如下:(1)新中國成立后,選舉制度經(jīng)歷半個多世紀的發(fā)展,正在逐步走向完善;
(二)進行新課1、動能與勢能的相互轉(zhuǎn)化演示實驗1:如右圖,用細線、小球、帶有標尺的鐵架臺等做實驗。把一個小球用細線懸掛起來,把小球拉到一定高度的A點,然后放開,小球在擺動過程中,重力勢能和動能相互轉(zhuǎn)化。我們看到,小球可以擺到跟A點等高的C點,如圖甲。如果用尺子在某一點擋住細線,小球雖然不能擺到C點,但擺到另一側(cè)時,也能達到跟A點相同的高度,如圖乙。問題:這個小實驗中,小球的受力情況如何?各個力的做功情況如何?這個小實驗說明了什么?學(xué)生觀察演示實驗,思考問題,選出代表發(fā)表見解。小球在擺動過程中受重力和繩的拉力作用。拉力和速度方向總垂直,對小球不做功;只有重力對小球能做功。實驗證明,小球在擺動過程中重力勢能和動能在不斷轉(zhuǎn)化。在擺動過程中,小球總能回到原來的高度。可見,重力勢能和動能的總和保持不變。即機械能保持不變。
3.適用條件(1)萬有引力定律只適用于質(zhì)點間引力大小的計算。當兩物體間的距離遠遠大于每個物體的尺寸時,物體可以看成質(zhì)點,直接使用萬有引力定律計算。(模型)研究相互接觸的兩個人之間的萬有引力時,不能把他們看作質(zhì)點。(2)當兩物體是質(zhì)量均勻分布的球體時,它們間的引力也可直接用公式計算,但式中的r是指兩球心間距離。研究太陽和地球之間的萬有引力,可以把它們看作質(zhì)量均勻的球體。當研究物體不能看成質(zhì)點時,可以把物體假想分割成無數(shù)個質(zhì)點,求出兩個物體上每個質(zhì)點與另一物體上所有質(zhì)點的萬有引力,然后求合力,這是微積分的思想。萬有引力定律產(chǎn)生于對太陽系行星運動的研究,但它對物質(zhì)運動的適用性卻要廣泛得多??梢赃@樣說,宇宙中凡有引力參與的一切復(fù)雜的現(xiàn)象,無不要歸結(jié)到這樣一條十分簡潔的定律之中,這不能不使人驚嘆宇宙萬物超乎尋常的和諧及人類理性思考所具有的統(tǒng)攝力。
世界能源問題的解決途徑是什么?能源,是人類敕以生存和進行生產(chǎn)的不可缺少的資源.近年來,隨著生產(chǎn)力的發(fā)展和能源消費的增長.能源問題已被列為世界上研究的重大問題之一.解決世界能源問題的根本途徑,主要有兩個方面:其一是廣泛開源,其二是認真節(jié)流.所謂開源,就是積極開發(fā)和利用各種能源.在繼續(xù)加緊石油勘探和尋找新的石油產(chǎn)地的同時,積極開發(fā)豐富的煤炭資源,還要大力開發(fā)水能,生物能等常規(guī)能源,加強核能、太陽能,風(fēng)能、沼氣,海洋能,地?zé)崮芤约捌渌鞣N新能源的研究和利用,從而不斷擴大人類的能源資源的種類和來源.所謂節(jié)流,就是要大力提倡節(jié)約能源.節(jié)能是世界上許多國家關(guān)心和研究的重要課題,甚至有人把節(jié)能稱為世界的“第五大能源”,與煤、石油和天然氣、水能、核能等并列.在節(jié)能方面,在有計劃地控制人口增長的同時,重點要發(fā)揮先進科學(xué)技術(shù)的優(yōu)勢,提高各國的能源利用效率.
1、教師先演示投影:把小鋼珠放在黑墨水瓶蓋里轉(zhuǎn)一下(內(nèi)有一點點墨水),再放在半圓形有機玻璃軌道上運動并飛出,讓鋼珠在白紙上留下痕跡,同樣在3/5半圓周,4/5半圓周上運動飛出,讓學(xué)生猜測飛出方向由什么特點?(有機玻璃板說明:厚約5毫米,略小于小鋼珠直徑,圓弧半徑15厘米,MN邊稍長些,以便過MN做直線,根據(jù)半徑大小確定圓心O位置。)學(xué)生猜想:切線方向師:已知圓弧半徑為15厘米。如何驗證?請用幾何方法作圖驗證。生:標出飛出點和圓心,做圓心和飛出點的連線,用量角尺量出該連線和飛出軌跡直線的夾角,是否90度。2、再分組實驗,提醒同桌配合,小心鋼珠滾跑。實驗完畢,要求作圖驗證,并互相討論交流。3、交流和結(jié)論:師:要引導(dǎo)學(xué)生得出正確的科學(xué)結(jié)論:“圓周運動的物體的速度方向為該點的切線方向”,而不能直接得出“曲線運動的的物體速度方向為該點的切線方向”。