What did we learn from studying acoustic black holes
a
r
X
i
v
:g r
-
q
c
/
2
4
7
9
v 1
2
6
A
p
r
2
2
What did we learn from studying acoustic black holes ?Renaud Parentani ?February 7,2008Abstract The study of acoustic black holes has been undertaken to provide new insights about the role of high frequencies in black hole evaporation.Be-cause of the in?nite gravitational redshift from the event horizon,Hawk-ing quanta emerge from con?gurations which possessed ultra high (trans-Planckian)frequencies.Therefore Hawking radiation cannot be derived within the framework of a low energy e?ective theory;and in all deriva-tions there are some assumptions concerning Planck scale physics.The analogy with condensed matter physics was thus introduced to see if the asymptotic properties of the Hawking phonons emitted by an acoustic black hole,namely stationarity and thermality,are sensitive to the high frequency physics which stems from the granular character of matter and which is governed by a non-linear dispersion relation.In 1995Unruh showed that they are not sensitive in this respect,in spite of the fact that phonon propagation near the (acoustic)horizon drastically di?ers from that of photons.In 2000the same analogy was used to establish the ro-bustness of the spectrum of primordial density ?uctuations in in?ationary models.This analogy is currently stimulating research for experiment-ing Hawking radiation.Finally it could also be a useful guide for going beyond the semi-classical description of black hole evaporation.
The motivation for the analogy
The semi-classical description of black hole evaporation is based on the hy-pothesis that the dynamics of the system (black hole +radiation)can be well approximated by treating the gravitational ?eld classically.In this case the quantized radiation ?eld φobeys the d’Alembert equation
1
?g ?μ√
?Laboratoire de Math′e matique et Physique Th′e orique,CNRS-UMR 6083,Universit′e de Tours,Parc de Grammont,37200Tours,France.
1
away its mass by emitting a thermal?ux with a temperature given by T=κ/2πwhereκis its surface gravity.
The hypothesis of having treated gμνclassically?nds support in the fact that Tμν ,the expectation value of the energy-momentum tensor ofφ,is regular.By solving Einstein equations driven by Tμν ,one then?nds that the evaporation stays adiabatic as long as the residual mass of the hole is much larger than the Planck mass,see e.g.[2].
However,the validity of the semi-classical description becomes dubious when inquiring about the origin of Hawking quanta.Eq.(1)predicts that they emerge from con?gurations localized extremely close to the horizon and characterized by ultra-high frequencies(when measured by an infalling observer).This is speci?c and intrinsic to horizon quantum physics as it follows from free propagation near an event horizon and from second quantization.The in?nite gravitational redshift from the event horizon implies that during the last stage of the collapse the radiation emitted by the body is redshifted according to
λ(t)∝?e?κt,(2) where?is the emitted frequency andλthat received on J+.Classically,there is thus no appeal to high frequencies since the initial frequencies?are bounded. On the contrary,Hawking quanta emerge from vacuum?uctuations with very high?precisely because these are redshifted as in Eq.(2).Indeed,the steady character of Hawking radiation is achieved at time t by referring to vacuum frequencies which grow according to?(t)∝κeκt,see Eq.(3.34)in[2].
Hawking radiation therefore cannot be derived within the framework of a low energy e?ective theory.Moreover since Planck scale physics is unknown,it is important to determine if/why the asymptotic properties of Hawking radiation could be insensitive to it.From the outset[3]this question has been the principle motivation for studying acoustic black holes.
The acoustic black hole geometry
The concept of acoustic black hole arises from the analogy between light prop-agation in a curved background and sound propagation in a moving?uid[3,4]. Consider a vorticity-free?ow of a barotropic?uid.The velocity?eld can be written as v=?Ψand the pressure P is related to the densityρby an equation of state P=P(ρ).Consider also the equation of continuity and Euler equation. Then linearize these three equations about a background solution,v B=?ΨB, P B,ρB,and consider the equation forψ=Ψ?ΨB,see[4]for details.Verify thatψobeys Eq.(1)when introducing the4D acoustic metric g acμνgiven(up to a conformal factor)by g ac tt=?(c2s?v2B),g ti=?v B i,g ij=δij.The velocity of sound c s is given by c2s=dP/dρ.
To obtain an acoustic geometry which behaves like that of a black hole, one must consider a?ow which becomes supersonic without developing any shock wave.A well-known device(by hydrodynamicians)which realizes this is the Laval nozzle:a pipe wherein|v B|reaches c s at its narrowest radius.
2
When considering a?ow to the left in the x-direction,the velocity behaves as
v B(x)=?c s+xκac and the acoustic horizon is located at x=0.In the near horizon region,for x?c s/κac,null(retarded)geodesics behave like
x(t)=x0eκac(t?t0).(3) Hence,for x<0,right moving sound waves are carried away to the left by the supersonic?ow.For x>0instead,they propagate to the right and their
frequencies are redshifted according to Eq.(2)withκ=κac.
Thus,if the phonon?eldψis second quantized and if its state is regular
across the horizon,the standard treatment[1,2]applies.It tells us that a con-
stant?ux of phonons at temperature T ac=κac/2πwill be emitted against the ?ow,to the right.The quantization of the phonon?eld is physically pertinent
in He4and in Bose-Einstein condensates(BEC).The regularity of the state of
ψrequires that the?ow v B(x)be regular across the horizon.
The usefulness of the analogy
So far we have not learned much because we have not yet taken into account the
fact that the dispersion relation of phonons is not linear when the wave length
approaches the inter-atomic distance,d c.Three possibilities can be obtained. Two can be modeled by
?2=c2s k2[1+ξk2d2c+O(k4)],(4) withξ=±1.ξ=1is realized in BEC and leads to supersonic propagation.
ξ=?1is realized in He4and leads to subsonic propagation.The third case
describes propagation in an absorptive medium such as a viscous?uid[4].It is governed by a correction term,the bracket in Eq.(4),given by[1?i|k|d c].
When taking into account the non-linearities of Eq.(4)while deriving the
production of Hawking phonons,one can test if the asymptotic properties of the?ux are sensitive to these non-linearities.In1995Unruh[3]showed(nu-
merically and forξ=?1)that they are not sensitive when T ac?c s/d c and when the initial state is vacuum for??T ac.These conclusions are now un-
derstood analytically,see[5]for a review.In spite of this absence of asymptotic
modi?cation,when propagating backwards in time a mode(or better a wave packet),one?nds that its near horizon propagation is dramatically modi?ed when its blue-shifted frequency reaches the critical frequency?c=c s/d c,see [6]for schematic representations of the modi?ed trajectories.
Being insensitive to high energy physics,the asymptotic Hawking radiation
is truly a low energy O(T)phenomenon.This reinforces our con?dence in the low energy predictions of the semi-classical treatment but does not take us any further concerning its dubious high energy predictions.
3
In?ationary models
In in?ationary scenarios,the primordial density?uctuations?nd their origin in
the non-adiabatic evolution of the non-homogeneous modes of the in?aton which
were in their vacuum state at the onset of in?ation.Given the exponentially growing redshift during in?ation,their initial frequency?was proportional to
e H?t,where H is the Hubble constant and H?t is the number o
f e-folds durin
g in?ation.If the latter is taken to be larger than～70(whic
h is the minimal
number for in?ation to work when the adiabatic era starts just below GUT
scale,near1015Gev)there is an appeal to Planckian physics.Therefore the doubts concerning Hawking radiation apply here as well[5].Thus the appeal to
modi?ed dispersion relations can also be called upon to see if the scale-invariance
of the primordial?uctuations spectrum is a?ected by modi?cations of Planck scale physics[7].
As in black hole physics,the properties of the spectrum are robust.The two conditions guaranteeing this robustness are the adiabaticity of the evolution
from Planck scale to that of H,and the regularity of the initial con?gura-
tions.The adiabaticity essentially follows from scale separation,M P lanck?H, whereas the second condition is severely constrained by self-consistency in the
following sense[8].The very existence of in?ation implies that the dominant
term in the Friedman equation is the in?aton potential energy.Thus the contri-bution of the other modes must be negligible.When H?M P lanck and when in?ation lasts more than70e-folds,this condition requires that the initial state of the modes observed today be vacuum.
Experiments?
Can we conceive and realize experiments in which Hawking quasi-particles could be measured?We used the term“quasi-particles”rather than phonons to em-phasize that in condensed matter there is a large variety of collective excitations which can propagate in e?ective metrics.At present it is not clear which mate-rial is the most suitable for our purpose.Another challenge is to build a regular horizon enclosing a trapped region.But probably the main di?culty is to get a su?ciently high temperature.Indeed it does not seem easy to get T ac>10?6K.
To overcome the detection of these soft quanta,one should perhaps con-sider a pair of acoustic holes.A natural feature of acoustic holes is to come in pairs:it su?ces to reduce the velocity?ow v B so as to re-cross the sound velocity.Moreover this second crossing leads to a white hole.And white holes are unstable.This instability would show up di?erently according the sign ofξ. For positiveξ,one would obtain a self-amplifying?ux of soft phonons,a laser e?ect,see[9].On the other hand,forξnegative,the“partners”of Hawking quanta would leak out of the white horizon with a frequency close to the cuto??c=c s/d c and would thus be easier to detect.
4
Orienting research on Quantum Gravity?
Even though this is clearly a delicate enterprise and one which might turn out to be misleading,it has been one of the major reasons to study acoustic holes. Let us take some risk and present our opinion as it stands today.
Besides the insensitivity of asymptotic properties,we have also learned that for all dispersion relations but the scale invariant one d c=0,there is no
appeal to unbounded frequencies.[When the gradient dv B/dx vanishes for x?x horizon?d c,the frequency of a backwards in time propagated wave packet stays of the order of?c for bothξ=±1,without any further blueshift.
One learns from this that the stationarity of Hawking radiation now results,as in the Golden Rule,by a steady increase of the density of modes at some?xed frequency.This is not what is found when there is no dispersion,see Eq.(3.34) in[2].]This suggests that the quantum gravitational interactions neglected in the semi-classical treatment might introduce a new scale d QG which could act on light propagation near the event horizon as d c did on phonons.In order words,instead of questioning the robustness of asymptotic properties,we are lead to question is?=k robust?
I would claim probably not.Because?=k follows from Eq.(1)which re-sults from a linearisation procedure:when starting from a quantum formulation of black hole evaporation,Eq.(1)is obtained by discarding all?uctuations of gμνaround the mean metric,a solution of the semi-classical Einstein equations. A?rst order analysis shows that the e?ects of metric?uctuations on con?gura-tions giving rise to Hawking quanta grow like1/(r?2M).Therefore a taming mechanism is bound to occur.This has been substantiated in[10]where it is shown that vacuum energy?uctuations engender metric?uctuations whose random properties induce a damping similar to that obtained by puttingξ=?i in Eq.(4).That near horizon quantum gravitational interactions should induce dissipative e?ects was anticipated in[2].
Acknowledgements
I wish to thank the organizers of the Journ′e es Relativistes in Dublin,as well as those of the ESF-COSLAB meeting in London for the invitation.I also wish to thank Ted Jacobson for many discussions.This work has been supported by the NATO Grant CLG.976417.
References
[1]S.W.Hawking,Commun.Math.Phys.43(1975)199.
[2]R.Brout et al.,Phys.Rep.260(1995)329,and refs.therein.
[3]W.G.Unruh,Phys.Rev.Lett.46(1981)1351;T.Jacobson,Phys.Rev.D
44(1991)1731;W.G.Unruh,Phys.Rev.D51(1995)2827.
[4]M.Visser,Class.Quant.Grav.15(1998)1767.
5
[5]T.Jacobson,Prog.Theor.Phys.Suppl.136(1999)1,and refs.therein.
[6]R.Brout et al.,Phys.Rev.D52(1995)4559.
[7]J.Martin and R.Brandenberger,Phys.Rev.D63(2001)123501;J.
Niemeyer,Phys.Rev.D63(2001)123502.
[8]J.Niemeyer and R.Parentani,Phys.Rev.D64(2001)101301.
[9]S.Corley and T.Jacobson,Phys.Rev.D59(1999)124011.
[10]R.Parentani,Phys.Rev.D63(2001)041503;Int.J.of Theor.Phys.40
(2001)2201-2216,and refs.therein.
6
what did you buy教学设计
Module 2 Unit 1 What did you buy ？ 教学目标 知识目标： 1、能听说读need, food, shopping list, cheese, how much, egg 。 2、理解学习句型：How many / How much did she say? 能力目标：能在实际情景中运用How many …did she say? How much…did she say? 谈论购买物品的数量. 情感目标：通过对话感受西方文化，同时培养学生良好的生活习惯，做一个文明礼貌的学生。教学重点：新学单词和句型的教学。 教学难点：会运用句型How many / How much ?did she say?在实际生活中学会如何用英语进行购物。 教学准备：点读机、卡片、一体机。 教学过程 Step 1 Warmer： 1、小组内交流 小组长检查：动词过去式、单词及短语的拼读情况；全组交流疑惑问题，简单的组内解决。解决不了的组长记录下来，准备全班交流时提出。 2、全班交流展示 （1）指生拼读单词；让两名学生一问一答向全班同学介绍自己上星期天做的事情。 Eg: What did you do yesterday? I watched TV yesterday . （2）各小组推荐优生（或集体）进行展示。 （3）质疑问难（其他小组能解决的可帮助解答，解决不了的老师进行讲解）。 【设计意图：生生活动复习过去式，为本课的学习做铺垫。】 3、全班齐唱英语歌曲：Where did you go ? 【设计意图：通过让学生唱歌曲，为学生营造轻松的英语课堂。】 Step 2 Leading in Tell students：Ms Smart’s home and Lingling are going to have a picnic. They need some food for their picnic. So they went to the supermarket. Listen: What did they buy? 【设计意图：直接引入课题，让学生明白本节课的学习语境。】
Module 2 Unit 1 What did you buy教案
Unit 1 What did you buy? 教学目标： 1、知识目标 Listen say and write:list need first can lost how much cheese any Listen say and understand: What did you buy? How many bananas did you buy? 2、能力目标 Listen say and understand: What did you buy? How many bananas did you buy? 3、情感目标 通过看听说演唱等活动,使学生产生学习英语的兴趣,树立学好英语的信心. 教学重点： Words: can some any need cheese how much 教学难点： Sentence: What did you buy? How many bananas did you buy? 教学过程： Step 1: Warming up 1、Greetings 2、Sing a song: 《Fruit》 Step 2: Lead in
Ask: Do you like fruit? Which fruit do you like? Can you buy things at the supermarket? 21世纪教育网版权所有 Today we’ll learn Module2 Unit1What did you buy? Step 3: Presentation 1、Learn the words(多媒体出示图片，然后显示单词，猜词、认读和领读): Fruit: banana apple pear watermelon orange Food: egg tomato potato A shopping list: make a shopping list Need: I need a banana. We need a shopping list. You need food for picnic. Cheese:不可数名词，不能加s First 首先、第一，日常口语交际可以用到 Can 能我们可以说I can Lose 过去式lost 2、Learn the sentences: How many apples did your mum say? 讲解How many 后面跟可数名词的复数 可数名词例如：books apples bananas cups 讲解How much 后面跟不可数名词 不可数名词例如：rice milk
最新外研版小学英语五年级上册What did you buy公开课教学设计
What do you buy?教学设计 一、教学目标 1．语言知识目标 （1）掌握单词：“sausages, carrots, cabbage, potatoes”。 2．语言能力目标 会用“what do you like? what don’t you like?”询问周围人的喜好，并用“I like...but I don’t like...”来描述自己的喜好。 3．情感态度目标 培养学生节约粮食、养成合理饮食的好习惯。 二、教学重点与难点： （1）掌握单词：“sausages, carrots, cabbage, potatoes”。 （2）会用“what do you like? what don’t you like?”询问周围人的的喜好，并用“I like...but I don’t like...”。来描述自己的喜好。 三、教学用具 单词卡片、多媒体课件、视频、实物。 四、教学过程 （一）导学（3分钟） Warm-up 1、观看水果、食物儿歌视频。 2、Talk about food、fruit 、drink(work in pairs) 3、介绍学习目标。 （二）自学新词（10分钟） （1) I can learn by myself（我会自学）(4分钟) 跟录音、跟同学、跟教师学习sausages, carrots, cabbage, potatoes 。（2） I can practice（我能熟练）(4分钟)
同学们自读单词，力求熟练。并把自己读不准的单词做上记号。可向同伴和老师求助。 T:点拨疑难（了解单复数） 利用实物和PPT向同学们展示： sausage a sausage two/three sausages, carrot a carrot two/three carrots potato a potato two/three potatoes （3）I can response（我反应快）(2分钟) 小组合作学习：小组成员轮流担任指挥。指挥快速地、变换顺序地展示单词卡片，同伴快速说出相应的单词。先让其他同伴一起答，然后再让同伴单独答。 （三）自学句型（6分钟） （1）自读、同桌读、男女读、跟录音学句型“what do you like? what don’t you like?”，师引导学生用“I like...but I don’t like...”。 （2）师做表情和动作并提问“what don’t you like?”，引导学生理解句意并回答“I don’t like……” （四）小组互学。（6分钟） （1）小组内一人扮演快餐店的服务员，一人扮演顾客进行选购，运用运句型what do you like? what don’t you like?”，及答句“I like...but I don’t like...”来表演对话，每两个同学在练习时，其它同学要认真听，并指出说的不对的地方。 （2）小组长看一下组内成员的表演，选出最好的，要给予表扬。 （五）汇报展示（6分钟） 每小组选出优秀组给全班同学表演。 (六) 回顾提升（8分钟） 1、基础题☆ 选出不同类单词： （）1、A carrot B cabbage C sausage
最新外研版小学英语五年级上册What did you buy教学反思
《How many do you want?》教学反思 本课的教学内容为《小学新标准英语》第五册第2模块第1单元 《How many do you want?》。本课重点是词汇need 、food、 shopping list 、cheese 、how much、 kilo,句型How many did you buy? 课文内容相对较容易。因此，我在课堂上围绕重点内容安排了形式多样的活动： 一、准备一个袋子，告诉孩子们袋子里是装着我采购回来的东西，让他们猜一猜是什么？通过这一活动复习了有关的食物单词，如：banana、apple、orange、milk、fish、等，并由此引入新授单词need, list, cheese。 二、在黑板上事先画好的两个冰箱：（how many和how much）,先做示范，再让学生根据自己的理解将买回的食品放进相对应的冰箱里，并引导学生思考为什么要这么放？从而导入到可数名词与不可数名词。此教学更生动、形象，吸引了学生的注意力，并让学生理解和区分how many 和how much的用法。同时也发挥了学生的学习主动性，在教师的引导下思考知识的规律，这样更有利于孩子们牢固的掌握及运用新知识，也有利于孩子们思维能力的培养。 三、通过“最佳买卖”比赛，用新学的购物语言：A：How many eggs did you buy? B: twelve eggs .进行练习，此活动不仅巩固了新知识，而且通过奖励，使学生始终强烈的兴趣和信心，积极参与到语言实践中来，而且进一步巩固了新知识，突出了重点。 这堂课中，我总结了之前的教学，将好的经验与建议运用到自己的教学中来，如：在教授新单词时，结合句型进行教学，体现“字不离词，词不离句”的思想，比如，我在教“cheese”这个单词时，在学生掌握好行和义之后，引导学生用已学的句型进行口头表达：“Do you like cheese? I like cheese. 通过这样的方法，学生的理解能力有了提高。句型的练习也是先让学生模仿，等学生能正确运用时，引导学生进行扩展，这样学得既扎实又轻松。
M2 U1What did you buy
英语 《英语》（新标准）（三年级起点）五年级上册教学设计 Module2 U1 What did you buy? (Period1). 教学目标： 语言知识目标：What did you buy? How many…did you buy? How much did you buy? 单词：list, first, lost, cheese 知识技能目标： 能口头运用Wha t did you buy? How many …did you buy? 这类语句询问购物情况, “I bought .....” “We bought 12/13 apples....”这类语句陈述购物情况。情感态度目标：学生了解购物的礼节，以及有计划的购物。 教学重点与难点： 重点：Make the Ss use the following sentences correctly: “How many …did you buy? “We bought .....” “We bought 12/13 apples...” 难点：How to make a shopping list? 课前准备： 1、课本及CD。 2、课件。 教学过程： Step 1 Warm up (3’) 1.Greetings: T：What’s the weather like today? Ss: It’s sunny. T: What day is it today? Ss: It’s Thursday. 2.T: Look, what’s this? Ss: It’s a tree. T: Yes, and it’s a food tree. What are these? Ss: Apple, banana, ice cream, cake... 复习之前所学的食物单词。 Step 2 Presentation and practice (15’) 1.T: Last Sunday, I went to a picnic with my family. I prepared so many food. PPT 让食物消失，Now, can you still remember what did I prepare? Ss: Apple, banana… T: You are 59 students, so you can remember them all. But I can’t. So I made a shopping list. 教授新词list. 2. T: Look at the list, N.O.1 is...? Ss: bananas.
外研版五年级英语上册What did you buy(How much cheese did you buy)教案
Module 2 Unit 1 What did you buy ? Teaching goals: 知识与技能：Words: how much, how many, one kilo, one bottle, half a kilo； How many/much……did you buy? Sentences：How much cheese did you buy? Half a kilo.How many apples did you buy? 过程与方法：通过理解和对话掌握过去时一般疑问句的表达方法。 情感态度与价值观：学会运用过去时表达交流。 Teaching steps： Steps 1 Warming-up T: Good morning girls and boys. Ss: Good morning Miss Deng. T: Welcome to my class. Now, everyone let’s do it. Boys and girls, Are you happy now? Today we will learn the new lesson: What did you buy? T: What did you do yesterday? Ss: do homework , help my mother cook dinner T: NowI’m so happy to share something to you.YesterdayIhave to do dinner. Then I went shopping.Who can guess what did I buy? I bought…some apples, oranges, and fish, meat, some vegetables… Steps 2 Presentation Everyone if you go to the supermarket what do you want to buy? Nowprepare one paper, listen carfare and write down the massage. Q: What did dad ask Sam to buy? some fruit . And where is the fruit? –Sam ate it all. Boys and girls, maybe if you go to the supermarket maybe someone buy ice cream, hamburger, drink, but do you know what did Sam want to buy? Ok,close your book, next we listen the tape and answer the questions. Q: 1、Did dad make a shopping list? --- yes, he did. 2、Did they lose the list? --------- yes, they did. 3、Did they buy bananas? ----------- no, they didn’t. Steps 3 Practice
Module 2Unit 1 What did you buy
Module2 Unit1 What did you buy? 教学设计 一、教材分析（Text description） 本节课是小学英语五年级外语教学与研究出版社New Standard English小学英语三年级起点五年级上册Module 2 unit 1第一课时，课文的情境时Amy一家人要带Lingling去野餐。 M s Smart软泥怪Amy和Mr Smart去超市买些吃的，但是Mr Smart 问 Amy要买多少苹果，多少奶酪。Amy记住了要买四个苹果，但不知道要买多少奶酪。俩人回家后，Ms Smart问他们买了社么，Mr Smart和Amy 一一说明，结果发现忘了买香蕉，却多买了一打鸡蛋。主要运用句型What did you buy? How many bananas did you buy? How much cheese did you buy? 二、教学目标（Teaching objectives ） 1全体学生能运用单词list, need, first, can, lost, how much, cheese, any, use, over there.,听懂句子What did you buy? How many bananas did you buy? How much cheese did you buy? 2、全体学生能运用单词can, how much, any, use, half.能说What did you buy? How many bananas did you buy? How much cheese did you buy? 3、部分学生能认读并运用单词list, need ,first, lost, cheese, over there 三、教学重、难点分析（Important and difficult points） 1．重点：能听懂，并认读Part2 Listen and read表述的信件的内容。 2．难点：能用What did you buy? How many bananas did you buy? How much cheese did you buy?来询问别人.并学会问答。 四、教学准备（Teaching strategies） PPT课件、单词卡片 五、教学流程（Teaching procedures） Step1. Warm-up T: Good morning girls and boys. Ss: Good morning Miss Deng. T: Welcome to my class. Now, everyone let’s do it. (播放前一段歌曲，并跟着做动作if you are happy and you know it ) Boys and girls, Are you happy now? Today we will learn the new lesson: Step2: Lead-in T: What did you do yesterday? Ss: do homeworkers, help my mother cook dinner? T: Now I’m so happy to share something to you. Yesterday I have to do dinner. Then I went shopping. Who can guess what did I buy? I bought some apples, oranges, and fish, meat, some vegetables? Step 3: Presentation Everyone if you go to the supermarket what do you want to buy? (引导学生们回答有关这节课要讲到的单词，互动) Now prepare one paper, listen carfare and write down the massage. Q:What did dad ask Sam to buy? –some fruit. And where is the fruit? –Sam ate it all. (听一遍录音，全班回答后，然后打开课本全班跟录音读一遍并赞
小学五年级英语Whatdidyoubuy
Whatdidyoubuy 五年级英语教案 ●一、教材分析: Analysis of This Lesson 1、教学内容(Teaching contents ) 本课的教学内容为外语教学与研究出版社的三年级起点《新标准英语》第五册的Module2 Unit1 What did you buy? 2、教学重点(Teaching Points) Words:can food need cheese how much 3、教学难点(Teaching difficults) Sentence: What did you buy? ●二、教学目标 Teaching Aims 1、知识目标(Knowledge aim) Listen and say:shopping food need cheese Listen and understand: What did you buy? 2、能力目标(Ability aim) Listen and understand: What did you buy? 3、情感目标(Emotion aim) 通过看听说演唱等活动,使学生产生学习英语的兴趣,树立学好英语的信心. ●三、教学过程Teaching Procedures
Step 1:Listen to a song: Sing a song:Mary hand a little lamb. (设计意图:活跃课堂气氛,创设英语氛围,激发学生的学习兴趣) Step 2:Free talks: Hello.How are you? What’s your name? How old are you? (设计意图:通过过自由对话拉近师生间的感情,并通过询问年龄复习数字。) Step 3、Warm up: 1.导入list (1) 通过出示Mr Smart和Sam对话的模拟情景,引出list, I you want go shopping.You can make a shopping list. 紧接着说: Such as: name list; book list. 2.导入cheese: (1)Read together.bananas,apples,pears,and cheese. &nb
外研版五年级英语上学期Module2 Unit1 What did you buy练习(含答案)
外研版五年级英语上学期Module2 Unit1 What did you buy练习 （含答案） 一、选择合适的单词或短语填空。 1. We food for our party. 2. cheese did your mum buy? 3. Xiaoqiang his pen yesterday. 4. Did you an y bananas? 5. girls ar e there under the tree? 6. Let's do our homework. 二、单项选择。 () 1. Amy, go buy some eggs, please. A. or B. and C. but () 2. We didn't buy ap ples. A. any B. much C. some () 3. How much do you need? A. bananas B. milks C. water () 4. My little sister pears. A. like B. liking C. likes () 5. I need water my trip. A. to B. for C. with 三、将下列句子与相应的图片连线。
1. How much milk did she buy? A. 2. I'll make a shopping list. B. 3. He didn't buy any eggs. C. 4. How many bananas do you have? D. 5. Did you buy any vegetables? E. 四、情景交际。 () 1. 你想知道妈妈买了几个苹果，你应问 () 2. 春游时你不小心丢了书包，你会对妈妈说 () 3. 妈妈从超市回来，你会问妈妈 () 4. 你想告诉妈妈表妹Lucy喜欢香蕉，你应说 () 5. 妈妈想让你去买些水果，她会说 A. What did you buy, Mum? B. Go and buy some fruit, please. C. I lost my bag. 教育精品 D. Lucy likes bananas. E. How many apples did you buy?教育精品 五、用所给单词的适当形式填空。 1. Mr Smart is making a (s hop) list. 教育精品 2. How many (book) are there on the desk? 3. We can (go) home by bus. 4. First, (finish) your homework.
Whatdidyoubuy教学设计
单元 M2 U1 课题 What did you buy? 课型新授型 知识与能力 1 Enable the Ss to learn the words:need,food,cheese,kilo. 2 Make the Ss understand and use the new sentence patterns: “How many bananas did you buy？How much cheese did she say?” 3 Develop the Ss abilities of listening and speaking . 4 Distinguish the words:need,food,cheese, ,and can write many and much. 过程与方法 1 Review the words about need,food,cheese by game method. 2 Teach the text with the task-based method. 3 Do a survey by cooperative learning . 情感与态度 1 Faster the Ss consciousness of good cooperation. 2 Keep the Ss confidence in learning English. 重点 Make the Ss use the following sentences correctly: “ How many … did you buy？ “ Do you like…? ” 难点 How to make a shopping list? What do we need to buy? 教法 1 game method 2 task –based method 3 approach method 学法 1 cooperative learning 教学 准备 Tape-recorder, word cards, pictures 预习设计 The students should read the new words and lessons for five times,it can help the students understand the text. 教学过程二次备课 Step1： 1. Revise Review the last module’s words and lessons by PPT. T：last module we learnt the word “ did ”. go—went run—ran meet—met buy—bought 2.Learn the new words and lessons： Show the powerpoint to the students:There are some pictures of the words: need ,food,shopping list,cheese,kilo. Then play a game：high low voice,it can help boys and girls recite the words. Step2 T:What did you do yesterday？ Ss:I did my homework. T:Please guess:What did I do yesterday? S1:Maybe you went shopping. T:Yes,you are right.I went to a supermarket.I bought lots of things,look at the board: T:Can you speak out in English?… Step3 Today Lingling and Mr Smart go to the supermarket,too.Let us Look at it. 1.Firstly,the students should follow the tape—recorder,then circle the new words in the text.
英语新课标五年级上M2U1what did you buy全英教学教案
Steps 1 Warming up (3mins) T: Good morning girls and boys. Ss: Good morning Miss Deng. T: Welcome to my class. Now, everyone let’s do it. (播放前一段歌曲，并跟着做动作if you are happy and you know it ) Boys and girls, Are you happy now? Today we will learn the new lesson: Module2 Unit1 What did you buy? (板书题目) T: What did you do yesterday? Ss: do homeworkers, help my mother cook dinner… T: Now I’m so happy to share something to you. Yesterday I have to do dinner. Then I went shopping. Who can guess what did I buy? I bought…some apples, oranges, and fish, meat, some vegetables… Steps2 Presentation (28mins) Everyone if you go to the supermarket what do you want to buy? (引导学生们回答有关这节课要讲到的单词，互动) Now prepare one paper, listen carfare and write down the massage. Q: What did dad ask Sam to buy? –some fruit. And where is the fruit? –Sam ate it all. (听一遍录音，全班回答后，然后打开课本全班跟录音读一遍并赞扬他们 perfect, big hands to yourself. ) Boys and girls, maybe if you go to the supermarket maybe someone buy ice cream, hamburger, drink, but do you know what did Sam want to buy?
Unit 1 Whatdid you buy_
Module2 unit1 What did you buy？ Step 1 Warming up 1、Greetings. 2、Sing a song--The London Eye. 给予学生肯定Good，you can sing very well. Step 2 Presentation 1、T: Boys and girls,yesterday,I went to the supermarket,this is my shopping list.（出示购物单。领读单词list。）What did I buy yesterday? S: Apples, bananas, a watermelon and nailao. T：Yes,I also bought some cheese.（领读单词cheese）how many apples did I buy? S:Six. T:Right.How much cheese did I buy? S:Half a kilo. T:Mr Smart went to suppermarket too, let’s see what did he buy? How much cheese did he buy? 2、listen to the tape and answer the questions. 学生听三遍并回答问题。教读单词first，need，any，lost。领读课文，跟磁带读。 Step 3 Practice 学生分角色朗读。小组读，找两组展示。 Step 4 Consolidation
1、Suggest you will go to the suppermarket to buy some food for your picnic.Make a shopping list. What do you need. 2、完成下面的对话，和搭档表演出来。 Amy：Hello，Tim. Tim:Hello,Amy. A：What did you buy for ...’s birthday party. T:I bought... A:How many/How much ...did you buy? T: I bought... A:Great.I can’t wait for the party. Step 5 Homework 1、Listen to the tape and read the text. 2、Make a dialogue with your partner and practice speaking.