答：放大镜的中间厚，边缘薄，光线在透过放大镜时会产生折射，因此会把物图像放大。六年级（下）Unit 6 Do not eat in class.
22、绿色植物的一些细胞能进行光合作用，制造养料，它们好像是一个个微小的工厂。[Presenting the 1st PPT about the introduction.]
Well, good afternoon ladies and gentlemen, I am very happy to meet you all here. Today，I am going to present Unit 6 Do not eat in class. Well, please look at the teaching material together. Well, this is a letter in the book. Students are required to read it through, have a look at it, try to write a letter to Zhao Jie, a boy who doesn’t like any subjects at all. [Presenting the 2nd PPT about the given letter.]
4、填埋场在填满垃圾以后，可以在上面修建公园、体育场、但是不能用来建筑房屋和种植庄稼。Well, I think my teaching aims should include the proper form of English letter, and second, how to write a letter in an idiomatic way. [Presenting the 3rd PPT about the teaching aims.]Well, to achieve these goals, I am going to arrange my teaching step by step [Presenting the 4th PPT about the teaching procedures]. Well, these are the steps, since so many, let me make it simple, actually, they are words, sentences and paragraphs. As we know that articles consist of words and sentences. So first, I would like to talk about the words. That is also the first step---revision. Well, you know, students have learned the names of the subjects in the former lessons. So, I am going to review the words by playing games with them.
一、填空：Here comes the first game: who can write more? [Presenting the 5th PPT about the 1st game]I am going to divide the students into two groups, for example boys and girls. They are given two minutes to rush to the blackboard and write down the subjects they know. The group which can write more will be the winner. Imagine how excited the students are, and at the same time, they are also reviewing the words. Well, what’s more, you may have noticed these two subjects, Physics and Chemistry. [Presenting the 6th PPT about the result of the game] Actually, these two subjects are not in this book. So, in this way, we can know that some students are showing us how much they know and all the students can also enlarge their vocabulary at the same time.
Well, after words, I would like to turn to sentences. Here comes the second game, who can make it longer? [Presenting the 7th PPT about the 2nd game] I am going to give students a word, for example subject. Which students can make it longer? Well, you please. Favorite subject. Good. A phrase appears. Longer? You please. My favorite subject is English. Well, a sentence appears. Even longer? My favorite subject is English, I like it very much, it is so interesting. [Presenting the 8th PPT about the answers of the game]Well, you can see students are constructing words into sentences step by step. Well, this is the revision part.
14、在太阳周围的八颗大行星，它们是水星、金星、地球、火星、木星、土星、天王星、海王星。After that, it is time to read. From now, I am going to show students the given material so soon. Actually, instead, I am going to show them those separated pieces. They should put them into the correct order[Presenting the 9th PPT about the reordering task]. You know before the lesson, I divided the whole letter into these four parts, why do I bother to do this? Well, you can see, in this way, students can put more attention to how to begin and how to end a letter. Then, they have a time, can have a chance to read through the whole article[Presenting the 10 th PPT about the reading material]. Well, at the same time, they should also pick out those well used words and sentences, and share them with the whole class. Then, they have a discussion “what information can we use? [Presenting the 11th PPT about the discussion task]Why talking about subjects? Of course, it is easy for them to find these information like these three ones ( time & day, teacher, reason ), because they are in the letter. But what else? Students need to think about that. Well, why? As we know it is easy to copy, but difficult to create. Sometimes, the given material gives us a good example, but sometimes, they may also limit students’ ideas. So they need to go further. As some teachers may prefer to offer the answers directly to the students. But I am not. I think teaching students how to learn is much more important than just teaching knowledge. So students should think about that by themselves. Well, this part is also a brainstorm to them. Till now, they have known so much. Since that, they should be given a chance to put what they’ve known into practice. So I prepare two practices[Presenting the 12th PPT about the 2 practices]. Practice number one, students have a Free Talk about their favorite subjects, if they can express themselves fluently and naturally, they won’t have much difficulty in writing them down. Well, second practice will be the real writing. They are given eight minutes to write a letter to Zhao Jie[Presenting the 13th PPT about the beginning of the letter]. Well, when they finish writing, six students get into a group, they exchange their letters and try to correct mistakes. Why they should do that? Well, teachers may have noticed that not many students have the habit of rewriting and correcting mistakes when they finish writing, and I want them to realize this is also very important.
Ok, after that, each group chooses two representatives, the best one and the one who has made great progress. Which two? I think not only those advanced students but also the less advanced students should be given a chance to show how good they are. Well, for example, yes, after that, some representative come to the front and show their letters to the whole class, but you can think it is a projector like this. This is a student’s letter and when all students finish writing it, they are welcomed to give comments. It is so-so, good or great. So which one? Can you find any beautifull sentences here? They are welcomed to give their ideas.
Well, here comes the last part[Presenting the 14th PPT about the homework]. Last part will be the homework. They can either write me an email or have a talk with some one or write an article about his or her favorite ********. I think both of these are highly connected with our daily life. So, students must be very interested. Ok, so that is all. Thank you very much!
21、人们发现银河系以外还有类似银河系一样庞大的恒星集团，如：仙女座星系、猎犬座星系，目前人类已发现了超过100亿个河外星系。（答辩问答）
答：①利用微生物的作用，我们可以生产酒、醋、酸奶、馒头和面包等食品。②土壤中的微生物可以分解动植物的尸体，使它们变成植物需要的营养素。③在工业生产和医药卫生中也都离不开微生物。Questions：Anyhow, I appreciate your teaching, and allow me to say so. My question is “ how do you check the achievements of the homework you send to your pupils?
6、蚜虫是黄色的，在植物的嫩枝上吸食汁液，每个蚜虫只有针眼般大小，在10倍放大镜下我们可以看清它们的肢体。25、意大利的科学家伽利略发明了望远镜，天文学家的“第三只眼”是天文望远镜，可以分为光学望远镜和射电望远镜两种。Answer：Well, about this question, I think, first, still the group work. They should exchange their letters and each group should also choose two representatives and hand in the letters or the articles they have written to me, and I correct them by myself. And then, put all these representatives’ works on the wall and show them to the whole class. By this way. Thank you!
8、铁生锈的原因是什么？人们怎样防止铁生锈？
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