1、The education of AmericaKey words: American education, elementary education, secondary education, high education, advantages of American educationAbstract: The education of American , is so called the best education in the world. Why do somany people have this opinion? Do you know the advantages of

2、its education? What are the difference between the American education and the Chinese education? Now I will illustrate the answer for you in the words below.Instruction part:America, as we all know, is one of the most developed country in the world. We say it is developed, not only on the science an

3、d finance fields, but also on the education field. That is why so many students go to America for studying every year.However, why we say the education of America is the best all over the world? And what is the advantages when it compared with the education of China? Now let us search the American e

4、ducation system together.Different from China, under the United States constitution, the Federal government has no power to make laws in the field of education; each state is fully responsible within its own territory. The Federal government can give financial help but not orders. Each state has an

5、educational administration, not subject to federal control, and the state authorities lay down general principles concerning the organization of schools and such matters as the ages of compulsory education.We can divide the progress of American education into three steps. Elementary education, secon

6、dary education and high education.Elementary education:In the United States elementary education begins at the age of six. Classes of students are divided into twelve academic levels called grades.At elementary stage, nearly all the teachers are women, mostly married. The atmosphere is usually very

7、friendly, and the teachers have for a long time now accepted the idea that the important thing is to make the children happy and interested. The old rigid and authoritarian methods of education were discredited in America rather a long time ago- so much so that many people now think that they have g

8、one too far in the direction of trying to make children happy and interested rather than giving them actual instruction.secondary education:The students go to high school automatically after finishing their elementary school education. There is no entrance exam. The high schools, junior and senior,

9、have a good reputation in the country. They take their responsibilities very seriously and not only in the classroom. They have guidance counselors to whom children can go privately if they have any special problems, especially about their careers.The high school student's day may be divided int

10、o nine periods: five for academic subjects, one session for physical education, a lunch period, and two study periods. The study periods may beused for visiting the library or participating in an extracurricular activity such as the school orchestra, newspaper staff, or math club. There are now some

11、 special high schools in America which train boys and girls for jobs - secretaries, mechanics, computer specialists, and accountants. Businessmen take an interest in such schools and encourage the teaching of salesmanship and business techniques. The fear of young people today is to grow up and find

12、 no job waiting for them. so they need no encouragement to work hard at school.high education:For a long time, America has led the world in higher, education, quantitatively at least. The aggregate number of U.S. institutions of higher education is, at last count, 3,280. This figure represents one i

13、nstitution for every 75,000 Americans. Slightly more than half of all institutions of higher education are privately supported many of them by religious groups.In American colleges and universities, a vast array of subjects is offered. The student can sample different fields of knowledge, but he usu

14、ally majors in one field during last two years of college. If he wishes, he may obtain professional training at the undergraduate level, for example, in accounting, teaching, journalism, or dramatics. Certain state colleges specialize in training agricultural experts and engineers.Most importantly,

15、they work intensively with students writing thesis or dissertations. Guiding master's and Ph. d. candidates through the final writing and examination stages of their programs may be seen as an extension of the teaching act; nevertheless, it takes up much faculty time. Here the faculty member bec

16、omes both critic and editor of manuscripts which maybe several hundred pages in length.Analysis and comment:Have said so much above, we can see that American education have lots differences between our Chinese education.First, the Federal government has no power to make laws in the field of educatio

17、n, so they dont have to think of the benefits of the government, what they should do is just teaching and tell students right from wrong. However in China, our schools are influenced by the government, so, the teacher have to tell us the positive things instead the fact about our government.Second,

18、unlike China, there is no entrance exam before we go to the high school in American, so that the American children can enjoy their children hood and train the interests on every fields. When we are busy on our exam, they are making their plan for the future!Now, I want to tell you a story about myse

19、lf.Before coming to the university, I was a good student in my middle schools teachers eyes for my diligent and enthusiasm. I listened to the teachers carefully and did my homework on time. a lot of people did it like me in my school, because we have the same dream-go to the good university. But I h

20、ave no idea about which collage I want to go and which field I like to be in in the future. I just went to the collage which has the highest mark. Now, Im i n grade two of university and I find I dont like my major at all. In fact, I am interested in the other subject. What should I do and what can

21、I doActually, I think we should have our plan of the future before we go to the university and we should have chance to touch every fields in our life to find out our best choice. At least, we shouldknow what we like and what we dont like. But we cant do that. What we can do is to practice more and

22、more for our exam.Conclusion:By saying so much above we can find that in the elementary education, the teacher try them best to make the children fell happy and make them interested in the things around them. In the secondary education the teachers main mission is to teach us how to make the plan of

23、 our future and tell us right from wrong. The high education, is the haven for us to learn what we like and what we need actually.第四節(jié)熱機(jī)效率和環(huán)境保護(hù)【教學(xué)目標(biāo)】知識(shí)與技能:1、建立熱值概念。知道熱值是燃料的重要特性,了解熱值的表示法和常見(jiàn)燃料的熱值,能利用熱值表進(jìn)行有關(guān)燃料放熱的簡(jiǎn)單計(jì)算。2、了解熱機(jī)效率。知道熱機(jī)工作時(shí)燃料釋放能量的主要流向,知道可以怎樣提高熱機(jī)效率以及提高熱機(jī)效率的意義所在。過(guò)程與方法:通過(guò)社會(huì)調(diào)查、分組交流合作,了解熱機(jī)效率及熱機(jī)帶來(lái)的負(fù)

24、面影響。情感態(tài)度與價(jià)值觀:了解熱機(jī)的利用與人類社會(huì)發(fā)展的關(guān)系,并能夠簡(jiǎn)述熱機(jī)使用產(chǎn)生的排放物對(duì)環(huán)境的不良影響,培養(yǎng)自覺(jué)的環(huán)保意識(shí),激發(fā)學(xué)生的社會(huì)責(zé)任感。【教學(xué)重點(diǎn)】燃料的熱值、熱機(jī)效率以及學(xué)生環(huán)保意識(shí)的培養(yǎng)?！窘虒W(xué)難點(diǎn)】熱機(jī)效率的理解和環(huán)境保護(hù)?！窘虒W(xué)準(zhǔn)備】木柴、煙煤、焦炭、汽油、柴油、酒精、液化石油氣(打火機(jī)中裝有等燃料樣本,多媒體課件,布置學(xué)生課前進(jìn)行有關(guān)環(huán)境污染方面的社會(huì)調(diào)查?！窘虒W(xué)方法】啟發(fā)式教學(xué)法,自學(xué)討論法,設(shè)疑教學(xué)法,類比教學(xué)法?！窘虒W(xué)過(guò)程】一、新課引入。無(wú)論是燒菜做飯,還是奔馳的汽車與火車,乃至直入蒼穹的火箭等都離不開(kāi)燃料。即從原始人類學(xué)會(huì)用火的那天起,至今,人們使用的能量絕大

25、部分還是通過(guò)燃料燃燒獲得的。那么燃料燃燒釋放的能量究竟有多少用來(lái)做了有用功?以及燃料的燃燒對(duì)環(huán)境會(huì)造成那些影響呢?今天我將和大家一道共同來(lái)學(xué)習(xí)“第四節(jié)熱機(jī)效率和環(huán)境保護(hù)”。(出示課題二、新課學(xué)習(xí):1、課件展示:木柴取暖、煤氣燒飯、鍋爐中煤炭燃燒、內(nèi)燃機(jī)車、飛機(jī)、輪船等,引出常見(jiàn)的燃料。2、設(shè)疑:常見(jiàn)的燃料有木柴、煤炭、汽油、酒精等,在燃燒時(shí)都會(huì)釋放能量,但它們釋放能量的能力是否相同呢?如果不同,那又如何來(lái)表示它們這種能力的大小呢?3、交流與討論:如何比較不同燃料燃燒釋放能量的能力的不同?注:如果學(xué)生不能回答,可由教師引導(dǎo):必須保證哪些量相同才能進(jìn)行比較?(燃料的質(zhì)量要相同,而且都要完全燃燒。4

26、、(由此引導(dǎo)學(xué)生給熱值下定義。(一、燃料的熱值定義:某種燃料完全燃燒釋放出的熱量與所用該燃料的質(zhì)量之比叫做這種燃料的熱值。用q表示。(出示板書。單位是J/kg,氣體燃料熱值單位是J/m3。思考:給熱值下定義時(shí)你認(rèn)為應(yīng)該注意哪些?強(qiáng)調(diào):熱值是燃料的重要特性,只和燃料的種類有關(guān),與質(zhì)量和是否完全燃燒無(wú)關(guān)。學(xué)生查熱值表,并表述木柴、液化氣熱值的物理意義。5、引導(dǎo)學(xué)生推導(dǎo)熱值的計(jì)算公式。由熱值的定義我們知道:1kg的干木柴完全燃燒釋放出1.2×107J的熱量;那么質(zhì)量為m kg的干木柴完全燃燒釋放出多少J的熱量,怎么計(jì)算?學(xué)生回答:mq。由此得出熱值的計(jì)算公式:Q=mq。思考:氣體燃料通常不

27、用質(zhì)量而用體積,因此計(jì)算氣體燃料放熱時(shí),公式應(yīng)該寫成?6、例題:計(jì)算4kg柴油完全燃燒釋放的熱量。解:查表可知q=3.3×107J/kg,所以Q=mq=4 kg×3.3×107J/kg=1.32×108 J。答:完全燃燒釋放的熱量為1.32×108 J。7、學(xué)生估算:在圖12-26所示的情況下,所需的干木柴、煙煤和汽油。交流與討論:在圖12-26中,而實(shí)際需要的干木柴、煙煤和汽油的質(zhì)量大大超過(guò)計(jì)算得出的數(shù)值,這是為什么?(燃料不能完全燃燒,燃燒時(shí)有熱損失(二、熱機(jī)效率。1、引語(yǔ):實(shí)際上熱機(jī)工作時(shí),并不能將燃料所蘊(yùn)藏的化學(xué)能全部用來(lái)對(duì)外做有用功,有很大一部分能量在工作的過(guò)程中損耗掉了。2、課件展示:課本第38頁(yè)圖12-27“熱機(jī)燃料燃燒能量走向示意圖”。由圖可知,真正能轉(zhuǎn)變?yōu)橛杏霉Φ哪芰恐皇侨剂先紵尫拍芰康囊徊糠帧?、引導(dǎo)學(xué)生由機(jī)械效率的定義得出熱機(jī)效率。定義:熱機(jī)轉(zhuǎn)變?yōu)橛杏霉Φ哪芰颗c燃料完全燃燒所釋放的能量的比值稱為熱機(jī)效率。用表示(即=Q有/Q總×100%。過(guò)渡語(yǔ):為了合理