第一篇：英文試講稿[范文模版]

We have discussed how to simplify a logic function using logic algebra.This method relies on the skill of the individual in applying the appropriate rules.Sometimes it is hard to be sure whether the logical function is already simplest form or not.Now we will introduce a new method, which is graphical, known as the Karnaugh map.It’s a tool for performing the simplification of logic function.2 first, we must know what is the K-map, and how to design it!Usually, the K-map is made up of 3 parts, and the 3 parts are variables, cells and binary numbers.Ok, we can get 2 k-maps, you should note each map includes 3 parts.Please remember the 3 parts, when you design k-maps, each of the parts is essential.we note the first map has 2 variables, it has 4cells, and the second map has 3 variables, it has 8 cells.So in an n-variable k-map, there are 2 to power n cells.4 then please observe the binary numbers on the upper and left side of the k-map.What do you discover from the changed values? Take the numbers on the upper side as example, look at the first map, the numbers is changed from 0 to 1 between adjacent cells, only one-bit is changed, of course, the number just has one-bit.On the second map, each number has 2 bits, the number is changed from 00 to 01, from 01 to 11, from 11 to 10, between the adjacent cells, there is only one-bit in the number changed.If we change the position of the 2 binary numbers, do you think this sequence is right? No!It’s not right, because the number is changed from 01 to 10, two bits are changed.So you should know there is only a single-variable value changed between adjacent cells.This is one of the K-map’s features.5 we look at other features.On the fist map, Cell 1’s adjacent cells are cell 2 and 3, it’s easy to understand.What are the cell 4’s adjacent cells? They are also cell 2 and 3.But on the second map, cell 3’s adjacent cells are cell 1, 4 and 7.This is easy to understand.Now please give the cell 1’s adjacent cells!You may list cell 2 and 3, it’s right, but it’s not all right, because you ignore the cell 5.Do you know what that is on the left side of cell 1? In fact, cell 5 is on the left side of cell 1, of course, cell 6 is on the left side of cell 2.In this case, adjacent cell include the cells located in the symmetric place.I hope everyone should note this.6 this is a 4-variable K-map.Please give the cell 11’s adjacent cells!Now you should know except cell 12 and 15, cell 3 and 9 are cell 11’s adjacent cells.Cell 3 is on the right side of the cell 11, and cell 9 is on the lower side.7 Ok, let’s summarize the feature of K-map.Fist, if a k-map has n variables, it must possess 2 to power n cells.Second, when you design a k-map, please note how to change the binary number on the upper and left side, there is only a single-variable value changed between adjacent cells.Third, it’s easy to find a cell’s adjacent cells, but I must emphasize that you don’t ignore these cells located in the symmetric place.Please care about these, it will easy for you to make use of K-map.8 after discussing K-map, let’s learn how to represent a truth table on k-map.Here is an example.This is a truth table of a 3-variable function, the knowledge about the truth table has been discussed earlier.The key step is to design a K-map, we know the function has 3 variables, the k-map also has 3-varibales, according to the features of k-map, there are 2 to power 3 cells in the K-map, they are 8 cells.Then the binary numbers will be written, you seem to note there is only single-variable value changed between adjacent cells, we have drawn a K-map.The second step is to mapping the logic function.It is an easy work for you to enter the value of the output variable Y in each cell.On the K-map, cell 0 corresponds to row 0, because the variables’ value are same, a is equal to 0, b is equal to 0, c is equal to 0, so we should enter 0 in cell 0.Cell 1 corresponds to row 1, a is equal to 0, b is equal to 0, c is equal to 0, enter 1 in cell 1.so we can draw a conclusion if all variables’ value on the map is same as those in the table, enter output value in corresponding cell.Ok, fig.5.3 gives the complete K-map of the truth table.Look at this example 2, this equation is in SOP form, first we should convert it into standard SOP, and then it can be represented on K-map.Observe this equation, this term and this term are not minterm.Although minterm and SOP form are discussed early, I think it’s necessary to review this knowledge.Minterm is also called standard product form, we look at example 2, the 3 terms are product form.This and this terms are only product form, they are not standard product form.But this term is standard product form.What’s minterm? A function has n variables, if the product term contains n variables, each variable may be in complemented form or in uncomplemented form.The product term is called a minterm or standard product form.11 of course, it’s easy to understand that if a function has n variables, there must be 2 to power n minterms.There are 3 variables A,B,C, so we can write 8 minterms.12 if the logical function is represented as a sum of minterms only, the function is said to be in standard sum of products form.This expression is not in standard SOP form, because this and this term are not minterms, and this expression is in standard SOP form.13 In fact, the logical function can be converted into standard SOP form.We know the C plus the complement of c equal 1, any term multiply 1 equal itself.So if the fist term multiplies this expression, it can be converted into two minterms, the two sides of the equal mark are equivalent.The second term can be converted into two minterms by the same way.We can get a standard SOP form.14 the represent the SOP form on K-map.15 According to minterm’s features, logical 1 corresponds to the original variable, logical 0 corresponds to complement of variable.When a equal 0, b equal 0, c equal 0, we can get this minterm, this term corresponds to this cell.In fact, the K-Map includes all minterms.16 the first term corresponds to this cell, so we enter 1 in this cell.the second term corresponds to this cell, so we enter 1 in this cell.the third term corresponds to this cell, so we enter 1 in this cell.the forth term corresponds to this cell, so we enter 1 in this cell.the fifth term corresponds to this cell, so we enter 1 in this cell.17 Ok.The equation in standard SOP form is represented on K-Map.18 this section is very important.It is well-known that K-map is perhaps the most extensively used tool for simplification of logical function.Ok, let’s look at how to simplify logical function using K-map.We will illustrate every step through a example so that you can understand this method easily.Let’s look at the fist step, Mark those cells with a 1 that correspond to the terms in expression.Here is an equation in standard SOP form.After designing a k K-map, enter 1s in corresponding cells.So we get fig 5.6.19 Form the 1s into the largest valid group.Some conditions limit the largest group.The group must be a rectangle, and must contain 2 to power i cells, i is equal 0, 1, 2, n.n is the number of variables.When you face this K-map, how to make valid group, on the left side, there are 3 ones, on the right side, there are 2 ones.The 3 ones couldn’t form a group, because it is not rectangle, and it has 3 cells, normally, the group should contain 1, 2, 3, or 8 cells.But these 2 ones can form a group, these and these also can form a group.u should remember this cell and this cell are adjacent, this cell is on the left side of this cell, this cell is in the right side of this cell, the two cells are the same.So these 4 cells should form a group, and it also satisfy the demand of form the largest group.ok we have formed two groups Step 3 each 1 on the map must be included in at least one group.The ones already in a group can be included in another group as long as the overlapping groups include noncommon ones.Please note this cell, it isn’t only in the group, but also in this group, it belongs to the two groups, these 2 groups are permitted.Because the 2 overlapping groups include noncommon ones.Except this cell , this group has this cell, this group has this, this and this cells.21 Step 4 will give us a rule about how to produce terms.Identify adjacent ones in a group, then see the values of the variable associated with these cells.If the variables will be different and they gets eliminated.Other variables will appear in ANDed form in the term.This map exist 2 groups.We observe this group first, the value of variable C is not changed, it is equal to 1.the value of A is also not changed, it’s equal to 0, but look at variable B, the value is changed from 0 to 1 between adjacent cells, variable B should be eliminated.The other two Variables A, and C will appear in ANDed form in the term, I have to emphasize that this term is written by the method of producing minterm.0 corresponds to complemented variable, 1corresponds to uncomplemented variable.So we get this term.Then we observe this group include 4 cells, the value of variable B is not changed, the others will be eliminated.We get the complemented B.two groups get 2 terms.22 step5 these terms are ORed to get the simplified equation in SOP form.This equation is previous, and this is simplified equation, in fact, it’s a simplest expression, these two equations are equivalent.Now, we have simplified a logical expression using K-map, do you find it is a simple and efficient method? Remember these 5 steps, they are useful.23 After this chapter, we should appreciate the two points.First, you must know how to design a K-map;it’s a basal and important knowledge.When you design a K-map, you should pay more attention to these details.Second, simplification a logical expression using K-map method, we know this method is simplest and most commonly used method, it’s an essential knowledge in this chapter and easy for you to be operated, I will give you some homework to practice yourselves, they are 7, 12, 16, and 18 on the page 188 and 189 respectively.Please treat them seriously, you will get promoted.

第二篇：試講稿

Good Morning,Ladies and Gentleman!I’m glad to have a chance to stand here.Today I will teach Unit 7 Hobbies.the first period for Grade four.Shall we start? It’s time for class.Good morning, everyone.Ok, sit down, please.Hello, boys and girls, I’m happy to see you.Can you sing an English song for me? Let’s stand up.And follow the video.Ok, are you ready?（播放視頻）What are you doing? I’m watching TV.I’m watching TV.What are you doing?I’m cooking.Cooking, cooking, cooking.What are you doing? I’m eating.Eating, eating, eating.En

Yummy!What are you doing? I’m washing my hands.Wow, you did a good job.Handclap.Look, la lala, I’m singing.I like singing.How about you? Who can answer the question “what are you doing?” just like me.If you do it, I will give you a paster.But you should put up you hand.got it?Oh, This boy, you want to have a try? You please.You like playing basketball? good, this for you, sit down please.The next one, who can? This girl please, you like dancing?greatI like dancing too, this for you, sit down please.Nest one, you please.Oh, you like eating? I’m hungry.This for you, sit down please.Anyone else?You please.You like watching TV, don’t watch TV for long time.This for you, sit down please.You are so clever.Now look at the screen, I’m singing, I like singing.I’m painting, I like painting.I’m reading, I like reading.51

Look at this picture.What’s he doing? He is riding a bike.帶讀 my hobby is riding a bike.ice-skate ice-skating.My hobby is ice-skating.listen to music

listening to music

watch TV

watching TV

play cards

playing cards

make models

making models

中英互譯

小白兔回家

good job!

游戲：policeman and thief警察抓小偷一個(gè)學(xué)生在座位上閉眼，另一個(gè)學(xué)生上臺(tái)做動(dòng)作，師提問：what’s your hobby? 全班回答句型，扮演小偷的同學(xué)做口型不出聲，其他同學(xué)通過聲音大小提示遠(yuǎn)近讀句子

小組討論句型what’s your hobby? My hobby is… Practice 1

總結(jié)所學(xué)單詞和句型

第三篇：試講稿

我的試講稿 各位同學(xué)好：

大家先憑第一感覺告訴我：“我會(huì)不會(huì)是個(gè)稱職的語文教師？”請(qǐng)你一定要說是啊，其實(shí)我對(duì)自己還是蠻有信心的，當(dāng)然對(duì)你們更有信心了，因?yàn)槟銈冞x擇了這里。

從今天開始就由我來給大家上語文課。說心里話，我更喜歡大家喊我導(dǎo)游而不是喊我老師。因?yàn)樯堆?？因?yàn)槲矣X得語文是個(gè)大觀園，里面妙趣橫生，景致萬千，接下來的日子我將帶著大家一起玩轉(zhuǎn)這個(gè)觀園。大家說，有沒有信心玩的高興玩的滿載而歸？

我先問一下，你會(huì)不會(huì)看著桌子上一大堆數(shù)、物、化等試卷而大嘆——路漫漫其修遠(yuǎn)兮，吾將上下而求索。眼看高考在際，你給自己打氣：長風(fēng)破浪會(huì)有時(shí)，直掛云帆濟(jì)滄海。大家說，你想不想出口成章？想不想緊跟時(shí)代節(jié)奏的同時(shí)，又不少文化底蘊(yùn)？

也許你要問：那要干什么？

回答是：學(xué)語文！

現(xiàn)在我問大家，喜歡語文嗎？（不喜歡）是不是覺得一聲平二聲揚(yáng)的很讓人郁悶？還有來一篇文章解剖似的很羅索？還有最讓你頭疼的是怎么也湊不成一篇作文？其實(shí)語文全不是你想像的那個(gè)樣子，他是一個(gè)大觀園，來自生活，來自己你內(nèi)心最真實(shí)的感觸，你現(xiàn)在看著外面的景色聯(lián)想一下，是想到函數(shù)了還是想到了各種優(yōu)美的詞匯了？肯定的說，人人本來就是一個(gè)文學(xué)天才。

所以呢，語文這個(gè)課只不過是一個(gè)工具，一個(gè)引子，由她來讓引出你心中所想所感，由她來放松你緊繃的神經(jīng)，所以利用好它，你，會(huì)更有自信！。

好，準(zhǔn)備好了吧？今天呢，我就帶著大家先熟悉一下這個(gè)大觀園。

進(jìn)園之前呢，我先問大家一個(gè)歇后語，猜對(duì)了才可以進(jìn)---小老鼠看書－－（咬文嚼字-）。對(duì)，小老鼠看書－－咬文嚼字。

咬文嚼字，其實(shí)語文不過是咬文嚼字?？墒怯袀€(gè)條件啊，那要看你怎么去咬了，是囫圇吞棗，不求甚解，還是向小老鼠學(xué)習(xí)：咬出樂趣，嚼出滋味，做一只有品位的小老鼠。

比如說“贏”這個(gè)字，由：亡、口、月、貝、凡 組成。我們先看： 亡字當(dāng)頭，就是說要有危機(jī)意識(shí)；其次是：口，就是要口才好，多說；再是：月，就是要月以繼日，珍惜時(shí)間；下一個(gè)是：凡，就是做平凡的事情，踏實(shí)，肯干；最后是：貝，就是成果。大家看看，只一個(gè)贏字就融合了那多的可推敲的東西，這可不是一般語言可以辦得到的。所謂中華文化博大精深，可見一斑。

現(xiàn)在進(jìn)了園，和孔子、孟子們“之乎者也”寒暄一陣之后，咱們先去看看文言文吧？這個(gè)大塊頭老是把咱們這些同學(xué)搞得暈頭轉(zhuǎn)向的，特別是諸子列國的人物列傳。那怎么辦呢？大伙放心，會(huì)有辦法的。不過我們只要把《史記》拜訪一下就行了。然后，再看幾篇名文。如《滕王閣序》：“落霞與孤鶩齊飛，秋水共長天一色?！痹趺礃?？其景讓大家心曠神怡吧？！日后我將和大家重游，將所有收歸已有?，F(xiàn)在咱們?cè)偃ヌ圃娝卧~那塊去看看，這里從來是大觀園中一大奇葩，多少風(fēng)流才子，多少愛國志土都在等著我們呢？在“云霞出海曙，梅柳渡江春”之時(shí)，你可以和高適執(zhí)手“莫愁前路無知己，天下誰人不識(shí)君?”也可以和歐陽兄共傷“離愁漸遠(yuǎn)漸無窮，迢迢不斷如春水”。自古讀書三境界：昨夜西風(fēng)凋碧樹，獨(dú)上高樓，望盡天涯路，衣帶漸寬終不悔，為伊消得人憔悴。眾里尋他千百度，驀然回首，那人卻在，燈火闌珊處。大家是不是覺得這塊風(fēng)景獨(dú)好？頗繞韻味？想不想在這里多呆一會(huì)兒？看那邊歐陽修，李煜正在爭(zhēng)論誰的春水用得好呢？“離愁漸遠(yuǎn)漸無窮，迢迢不斷如春水”和“問君能有幾多愁，恰似一江春水向東流?！贝蠹艺f哪一個(gè)好呢？我來再加上一句：“離恨恰如春草，更行更遠(yuǎn)還生”。這語文的世界就是這樣，可以讓大家看到不知不覺熏染上一種儒雅的氣質(zhì)，憑添幾許底蘊(yùn)和深度。

累了吧？咱們找個(gè)長亭歇一歇。那邊，元朝的純樸人民正在給我們打招呼呢！嗯，此時(shí)，崔鶯鶯和張生正在含淚送別呢：碧云天，黃花地，西風(fēng)緊，北雁南飛、、、、、、咱們最好還是別打擾了他們，讓他們多撒點(diǎn)離人淚，多吟幾句“遍人間煩惱填胸臆，量這大小車兒如何載得起？”

嗯，休息了一會(huì)之后，咱們想一想下一站是什么？散文，這個(gè)大家或許最不喜歡的了吧？特別是試卷上一大篇閱讀看來讓人乏味，其實(shí)也不盡然。今天，我就讓大家看看散文的美妙之處，也讓大家煽情一番，看到秋風(fēng)想到無情，看到落花流水想到漂泊異鄉(xiāng)，也感受一下通感的手法，聽聽花開的聲音，看看飛鳥的嫵媚、、、、、、大家靜下來想一下，心中最美或最恬靜的情景。那需不需要找個(gè)感情流放的出口？那就寫出來，定會(huì)妙筆生花。

到這里，大觀園就快讓咱們跑過來了，當(dāng)然這是走馬觀花，肯定意猶未盡，那最后就再讓咱們一起看看小說。這小說就最是貼近生活了，里面的情節(jié)人物其實(shí)都是現(xiàn)實(shí)生活的或貼切或夸張的寫法，想必大家更容易接受和親近的了。其實(shí)小說很簡(jiǎn)單，不就是那幾項(xiàng)嘛，大家都可以隨便編出個(gè)故事來。

游到現(xiàn)在，大家也累了，好好的整理一下，回味一下，到日后我還會(huì)繼續(xù)做你們的導(dǎo)游，和大家一同仔細(xì)欣賞這大觀園的妙處。在生活中學(xué)習(xí)語文，在歡笑中看花開，在淚水中看落葉。希望接下來的日子能和大家一起融入這個(gè)世界。

第四篇：試講稿

一、開場(chǎng)語

（敲門進(jìn)屋

面帶微笑 昂首挺胸）

尊敬的各位評(píng)委老師，大家上午、下午好！我是XX號(hào)考生。

二、導(dǎo)入

師：

上課，同學(xué)們好（鞠躬），請(qǐng)坐

（視頻類：適合直觀性強(qiáng)《地震中的父與子》）師：

同學(xué)們，上課之前,老師給大家播放一段關(guān)于XX的視頻，請(qǐng)大家認(rèn)真觀看，稍后呢老師會(huì)請(qǐng)同學(xué)們談一談?dòng)^看后的感受

（音樂類：適合主題性強(qiáng)、感恩、勵(lì)志）

師：

同學(xué)們，正式上課前我們先來聽一首歌曲、、、、、同學(xué)們你們聽懂這位歌者的訴說了嗎？這位同學(xué)說得很好。（有感情讀歌詞）原來他是在想我們傾訴XXXXX 導(dǎo)入方式

1、不提倡：回顧舊知識(shí)、檢查上節(jié)課所學(xué)

2、詩詞、文言文導(dǎo)入，疑問設(shè)置

名言導(dǎo)入

師：下面就讓我們一同走進(jìn)XXX的《XXXX》

三、整體感知

師：請(qǐng)同學(xué)們合上課本，老師來檢查一下同學(xué)們上節(jié)課學(xué)習(xí)內(nèi)容的掌握情況，我們來看大屏幕…

上節(jié)課我們學(xué)習(xí)了。。。這節(jié)課我們接著來學(xué)習(xí)這篇文章。

師：我們對(duì)文章的內(nèi)容不陌生了，1、那哪位同學(xué)來概括一下本文的主要內(nèi)容（寫人記事）

2、那哪位同學(xué)知道本文的中心論點(diǎn)是什么呢（議論文）

3、同學(xué)們默讀文章，邊讀邊思考這樣一個(gè)問題，文章的題目是《濟(jì)南的冬天》他獨(dú)具一格的特點(diǎn)是什么呢？課文是從什么角度，用什么手法來表現(xiàn)這一特點(diǎn)呢？（寫景）

四、析讀課文（注：小組合作交流）

師：復(fù)述主要內(nèi)容XXXX，那這是一個(gè)怎樣的父親和兒子呢，同學(xué)們可以選擇你們喜歡的閱讀方式，邊讀邊思考這個(gè)問題

同學(xué)們小組合作討論、文中哪里表現(xiàn)了父子之間的愛（寫人記事）

文章為我們呈現(xiàn)了XXXX，請(qǐng)同學(xué)們通過小組合作交流的方式，分析文章是從哪幾個(gè)方面對(duì)XX進(jìn)行描述的。（寫景）

文章是從開篇就提出中心論點(diǎn)嗎？那它是怎么引出文章中心呢（議論文）

人物形象塑造

1、正面描寫：典型事件、人物描寫方法

2、側(cè)面描寫：襯托 對(duì)比

提問語和過渡語

1、同學(xué)們請(qǐng)你們仔細(xì)讀讀這句話，你們認(rèn)為哪個(gè)詞用得好，為什么

2、老師想和大家分享一下老師的體會(huì)，我特別喜歡XXX句

3、請(qǐng)看大屏幕，老師將這句話略作了修改，同學(xué)們對(duì)比一下，這兩句所表達(dá)的內(nèi)容還一致了嗎？哪句表達(dá)的好，同學(xué)們可以小組交流這個(gè)問題，然后派一名代表來分享你們的交流結(jié)果

4、《觀潮》中“猶如千萬匹白色的戰(zhàn)馬齊頭并進(jìn)”

把“千萬匹”去掉行不行，不行，沒有了磅礴的氣勢(shì)，刪掉“白色”行不行，不行白色點(diǎn)名了潮水的顏色，與客觀事實(shí)相符。不說猶如部分，行不行，不行那就不形象生動(dòng)了。

5、重點(diǎn)部分：細(xì)節(jié)描寫、環(huán)境描寫、景物描寫

人物描寫

文章結(jié)構(gòu) 關(guān)鍵詞、句、段。

6、找出你最喜歡的句子讀一讀，要把感情融入進(jìn)去

7、文章中哪些地方也能夠表達(dá)這種情感，把它找出來分析一下

8、同學(xué)們，可以和你們小組成員交流分享一下你的收獲

9、你的眼光充滿期待就你吧

10、剛才你和你同桌討論的很激烈，就你吧

11、手舉得最高的就你吧

12、我們樂于助人的班長你來回答吧

13、你已經(jīng)迫不及待了，就你吧

14、小組展示的時(shí)間到了。哪個(gè)小組想先來說一說。有沒有想補(bǔ)充的

15、大家覺得他回答的怎么樣，這位同學(xué)，他認(rèn)為。。

在這位同學(xué)的補(bǔ)充下，答案就完整了

要注重生生評(píng)價(jià)！！

《地震中的父與子》

一、導(dǎo)入

視頻導(dǎo)入：地震視頻

相關(guān)綜藝節(jié)目

二、新授課

體現(xiàn)父與子的了不起的地方

父親：動(dòng)作、語言、神態(tài)、外貌 兒子：語言

其他人：動(dòng)作、語言

關(guān)鍵語句：描述情景、追溯原因、體會(huì)心情

1、沖向他兒子的學(xué)校

換字法 哪個(gè)動(dòng)詞用的好，模仿演示

把充換成“跑、走”不能體現(xiàn)父親的特別著急，作者在刻畫人物時(shí)被別細(xì)致

2、跪在地上大哭了一陣

想象，朗讀

為什么下跪啊，父親很絕望 腿軟了

同學(xué)們你見過你的爸爸下跪，大哭過嗎？過年回家祭祖看見過

為什么有如此不同的 變化 因?yàn)樗氲搅烁缸觽z約定的那句話

3、他挖了8個(gè)小時(shí)，12小時(shí)，24小時(shí)，36小時(shí)（想象）換字法。

時(shí)間的堆砌有畫面感，發(fā)揮想象 不同時(shí)間發(fā)生不同事件

4、這位父親雙眼直直的看著這些好心人

同學(xué)們想一想，“直直的”的是什么表情

充滿期待！尋求幫助??！上臺(tái)來模仿直直的眼神

5、他滿臉灰塵，雙眼不滿血絲，衣服破爛不堪，到處都是血跡。視頻！想象！誰的血。側(cè)面描寫

表演

分角色朗讀 三次勸阻

好心人：太晚了，沒有希望了

消防隊(duì)長：太危險(xiǎn)了，隨時(shí)可能發(fā)生大爆炸，請(qǐng)你離 警察：可這樣做，對(duì)你自己，對(duì)別人都有危險(xiǎn)，馬上回家吧 三次回答

誰愿意幫我懇求

你是不是來幫助我的 迫不及待 你是不是來幫助我的 崩潰

第五篇：試講稿（精選）

試講稿

一、情境導(dǎo)入

同學(xué)們，我給大家?guī)韮蓚€(gè)朋友，看看你們認(rèn)識(shí)他們嗎？（出示熊大、熊二）

是熊大和熊二，他們很貪吃，經(jīng)常為吃的而爭(zhēng)吵。有一天他們買了四個(gè)蘋果，兩罐蜂蜜，一塊大月餅。熊二說：“熊大，熊大，我要吃三個(gè)蘋果！”熊大說“不行，我們要分的一樣多，平均分。”每只熊分到兩個(gè)蘋果。

熊二想，我應(yīng)該懂得與熊大分享，每只熊分得一罐蜂蜜。還剩下一塊大月餅，熊大和熊二你看我，我看你，呆住了，不知所措。

同學(xué)們能幫他們分一分么？這就是我們今天要研究的知識(shí)——分?jǐn)?shù)的初步認(rèn)識(shí)（板書）

二、新課 認(rèn)識(shí)幾分之一

1、同學(xué)們真聰明，我都聽見有同學(xué)在說了，把這塊月餅平均分成兩份，每只熊得到半塊，下面哪位同學(xué)來分一分。（下去做一下給同學(xué)的動(dòng)作）同學(xué)把它對(duì)折，這樣就把一塊月餅平均分成了兩份，每只熊得到這樣的半塊，對(duì)不對(duì)？（貼月餅）同學(xué)們都在點(diǎn)頭，可是半塊怎么寫呢？誰能說說？那位同學(xué)的小手舉得真高，你說說吧，他說一半就是二分之一，你能寫出來么？（板書：1）

2這位同學(xué)了不起，不但知道一半用二分之一表示，還能把它寫出來，我們把掌聲送給他。這個(gè)數(shù)和我們以前認(rèn)識(shí)的數(shù)不一樣，跟老師讀一遍，二分之一。這一半是用二分之一表示，那另一半呢？也就是說，每一份都是這塊月餅的二分之一。把一塊月餅平均分成兩份，每塊是整個(gè)月餅的一半，也就是它的二分之一。

2、誰能像老師這樣說一說，這位同學(xué)你來說一說（學(xué)生語氣）A：把一塊月餅平均分成兩份，每份是這塊月餅的一半，也就是它的二分之一。它的指誰？這塊月餅。這位同學(xué)說的不錯(cuò)。B： 把一塊月餅分成兩份，每份是它的二分之一。已經(jīng)有同學(xué)有疑問了，他說：不是隨便分成兩份，是平均分成兩份。對(duì)，這位同學(xué)糾正的很及時(shí)，只有平均分成兩份，才能說每份是它的二分之一。數(shù)學(xué)的語言是很嚴(yán)謹(jǐn)?shù)膯眩?/p>

3、你還能找到像這樣的二分之一么？請(qǐng)大家從學(xué)具袋中任選一個(gè)圖形，折一折，我們看一下，三組分別是這樣的。

小結(jié)：同學(xué)們的想法都不錯(cuò)，無論是一塊月餅，一個(gè)圖形，只要把它平均分成兩份，每一份都是它的二分之一。（慢點(diǎn)，有起伏節(jié)奏）

4、我們認(rèn)識(shí)了二分之一，下面判斷一下哪個(gè)圖形的涂色部分可以表示二分之一？（先出示一個(gè)正確的二分之一，再出示一個(gè)錯(cuò)誤的二分之一。分別解釋。）同學(xué)們順利通過了檢測(cè)，老師還想增加難度，你們有信心么？

5、下面請(qǐng)大家獨(dú)立完成90頁二分之一以下的部分，誰來匯報(bào)一下？A：先說月餅的四分之一。B：第二幅圖是把一個(gè)圓平均分成三份，每份是它的三分之一，寫作1。C：第三

3幅圖是一張長方形紙已經(jīng)平均分成五份，看他涂得對(duì)不對(duì)？111、、這樣的數(shù)是分?jǐn)?shù)。

6、像

1、（板書）觀察一下有什么2345發(fā)現(xiàn)么？線的上面都是1，線的下面都是平均分成幾份，同學(xué)們觀察的很仔細(xì)，這樣的分?jǐn)?shù)都表示把一個(gè)物體或圖形平均分成幾份，其中的一份就可以用幾分之一來表示。這就是我們今天要學(xué)習(xí)的認(rèn)識(shí)幾分之一。（板書：幾分之一）

7、我們有自己的名字，分?jǐn)?shù)也有，你知道嗎，我們一起來學(xué)習(xí)一下，（先寫名稱，再說意義）分?jǐn)?shù)線表示平均分，分母表示平均分的份數(shù)，分子在這里表示其中的一份。那1就

3表示把一個(gè)物體或圖形平均分成三份，其中的一份是它的三分之一。讀作三分之一，同學(xué)們齊讀。（板書：三分之一）

三、動(dòng)手操作

下面請(qǐng)同學(xué)們小組合作，拿出學(xué)具袋中同樣大小的正方形紙，折一折，表示出它的四分之一。（下去走動(dòng)）展示大家的成果。（各組匯報(bào)貼圖）同學(xué)們積極動(dòng)腦想到很多辦法，請(qǐng)大家觀察一下，折法不同，涂色部分的形狀也不同，為什么涂色部分都是正方形紙的四分之一。請(qǐng)這組同學(xué)說，雖然折法不同，但都是把正方形紙平均分成四份，其中的一份就是它的四分之一。同學(xué)們說得對(duì)，雖然折法不同，但都是把正方形紙平均分成四份，其中的一份就是它的四分之一。也就是把誰平均分成幾份，就是誰的幾分之一。

四、鞏固練習(xí)

下面老師考考大家，做課本90頁做一做第一題，老師選一個(gè)，你們來說一說。同學(xué)們做的很準(zhǔn)確。（做一做第一題第三個(gè)，六分之一，說六分之一的意義）

五、全課小結(jié)

通過這節(jié)課的學(xué)習(xí)，你們有什么想說的嗎？看來同學(xué)們的收獲真不少，是的，把一個(gè)物體或圖形平均分成幾份，其中的一份就可以用幾分之一來表示！

同學(xué)們今天的表現(xiàn)真棒，下課。