一名优秀的教师在教学时都会提前最好准备,准备好一份优秀的教案往往是必不可少的。教案可以让学生更好地进入课堂环境中来,帮助授课经验少的高中教师教学。高中教案的内容具体要怎样写呢?以下是小编为大家收集的“《行行重行行》备课资料”相信您能找到对自己有用的内容。
《行行重行行》备课资料俗话说,凡事预则立,不预则废。作为教师就要在上课前做好适合自己的教案。教案可以让学生们能够更好的找到学习的乐趣,帮助教师能够井然有序的进行教学。你知道怎么写具体的教案内容吗?以下是小编为大家收集的“《行行重行行》知识点复习”仅供参考,欢迎大家阅读。
《行行重行行》知识点复习
【原文欣赏】《行行重行行》
行行重行行,与君生别离。
相去万余里,各在天一涯。
道路阻且长,会面安可知?
胡马依北风,越鸟巢南枝。
相去日已远,衣带日已缓。
浮云蔽白日,游子不顾返。
思君令人老,岁月忽已晚。
弃捐勿复道,努力加餐饭。
简介:
《行行重行行》出自《昭明文选》,《行行重行行》是产生于汉代的一首文人五言诗。
背景:
本首诗是爱情诗,是汉末动荡岁月中的相思乱离之歌。此诗抒写了一个女子对远行在外的丈夫的深切思念之情。
翻译:
你走啊走啊老是不停的走,就这样活生生分开了你我。
从此你我之间相距千万里,我在天这头你就在天那头。
路途那样艰险又那样遥远,要见面可知道是什么时候?
北马南来仍然依恋着北风,南鸟北飞筑巢还在南枝头。
彼此分离的时间越长越久,衣服越发宽大人越发消瘦。
飘荡游云遮住了太阳,他乡的游子不想回还。
只因为想你使我都变老了,又是一年很快地到了年关。
还有许多心里话都不说了,只愿你多保重切莫受饥寒。
字词:
重:又。这句是说行而不止。
生别离:是“生离死别”的意思。
相去:相距,相离。
涯:方。
阻:艰险。
胡马:北方所产的马。
越鸟:南方所产的鸟。“胡马倚北风,越鸟朝南枝”,是当时习用的比喻,借喻眷恋故乡的意思。
已:同“以”。
远:久。
缓:宽松。这句意思是说,人因相思而躯体一天天消瘦。
顾返:还返,回家。顾,返也。
“老”,并非实指年龄,而指消瘦的体貌和忧伤的心情,是说心身憔悴,有似衰老而已。
“晚”,指行人未归,岁月已晚,表明春秋忽代谢,相思又一年,暗喻青春易逝
弃捐:抛弃。
这两句的意思是说这些都丢开不必再说了,只希望你在外保重;一说是指这些都丢开不必再说,自己要努力保重自己,以待后日相会
作为优秀的教学工作者,在教学时能够胸有成竹,作为教师就要好好准备好一份教案课件。教案可以让学生能够听懂教师所讲的内容,帮助教师掌握上课时的教学节奏。关于好的教案要怎么样去写呢?考虑到您的需要,小编特地编辑了“Underthesea教学设计”,相信能对大家有所帮助。
Underthesea教学设计
WarmingUpprovidestwoactivitiestosparkstudentsinterestinthetopic.Ofcourse,beforetheclass,thestudentsmusthavegatheredsomeinformationtomakepreparationsforthisclass.Manykindsoftheirfavoriteseaanimalsarepresentedintheirvividpictures.Studentsareencouragedtointroducethemusingsomenewexpressionssuchasatanaquarium,onasnorkellingtrip.
Pre-readingisdesignedtofurtherstimulatetheirinterestinthetopicoftheunit.Meanwhile,studentsmayhavesomebasicinformationaboutthetext.
ThereadingpassageOldTomtheKillerWhaletellsabouttwoanecdoteswitnessedbythewriterhimself.Theteachercanfirstgetstudentstoskimthetextforthecharactersinthetwoanecdotesandgetthemainideaofeachanecdote.Thenletthemscanforfurtherunderstanding.Inordertoletstudentspayattentiontothewritersvividdescription,theteachercanaskthemtodoablank-fillingexerciseinpairstofindoutsomekeyverbsandverbphrases.Havingdonethis,studentsmusthavehadaveryclearunderstandingofthewholehuntingandsavingprocess.Tomaketheirunderstandingeasier,theteachershoulddealwithanylanguageproblemswhiletheyarereading.Andthenunderlinesomeusefulwordsandexpressions.
Forfurtherthinking,studentsareexpectedtoworkinpairsorgroups.Theywilldiscusstheproblemsandworkouttheanswerscooperatively,choosingareporterintheirgroup.Studentswillthinkactively,sovariousanswersarepossible.
Toconsolidatethecontentsofthereadingpassage,studentsshouldberequiredtoretellthepassageinthenameofOldTomorthebaleenwhaleorJameswithasmanykeywordsaspossible.
Attheendoftheclass,byholdingadebate,theteachercanarousestudentsinterestfurtheraswellasmakethemawareoftherelationshipbetweenmanandanimalsandtheimportanceofbanningwhaling.
三维目标
知识目标
1.Getstudentstolearntheusefulnewwordsandexpressionsinthispart:anecdote,annual,witness,accommodation,shore,opposite,yell,pause,telescope,teamwork,dive,depth,lip,urge,abandon,shark,relationship,help...out.
2.Letstudentslearnaboutseveraldifferenttypesofwhales,especiallythekillerwhales.
能力目标
1.Enablethestudentstolearntotalkabouttheirfavoriteseaanimals.
2.Developstudentsreadingabilitybylearningtoreadaboutthekillerwhalesandletthemlearndifferentlearningskills.
3.Developtheircreativethinkingability.
情感目标
1.Arousestudentsgreatinterestinseaanimals.
2.Makethemawareoftherelationshipbetweenmanandanimalsandtheimportanceofbanningwhaling.
3.Developstudentssenseofcooperativelearning.
教学重点
1.Readingcomprehensiontothetext.
2.Learningmoreaboutthekillerwhalesandunderstandingtherelationshipbetweenthekillerwhalesandthewhalers.
3.Importantwordsandexpressions.
教学难点
1.Therelationshipbetweenthekillerwhalesandthewhalers.
2.Developstudentsreadingability.
教学方法
1.Individual,pairandgroupwork.
2.Task-basedteachingandlearning.
3.Quiz,discussion,blank-filling,retelling,debate.
教学工具
Acomputerandaprojector.
教学过程
?Step1 Warmingup
1.Asksomestudentstoshowsomepicturesoftheirfavoriteseaanimalsandintroducethemtotheclass.Theintroductionshouldcovertheseaspects:
TheEnglishandChinesenameofyourfavoriteseaanimal.
Wheredidyoufindit?
Somefeaturesofit,itsdistribution,orlivingcondition.Anythingaboutitiswelcome.
Whydoyoulikeit?
Sampleintroduction:
①Myfavoriteseaanimalisdolphins(海豚).Ifoundthematanaquariumthissummerholiday.Dolphinsareverymeek(温顺的).Neitherastimidanimalsinvirginforestswhorunawayimmediatelytheydiscoverastranger,norasbeastsinremotemountainswhobarefangsandbrandishclawsthemomenttheyencounteraperson,dolphinsarealwaysfriendlywithpeople.Dolphinsandhumanbeingshavebeenonfriendlytermsallalong.
Ilikedolphins,becausedolphinsaretrulyintellectual.Theycanevenimitatesomepeoplesvoiceafteraperiodoftraining.Yet,dolphinshaveintelligencedifferentfromcommonanimals.Thevolumeandmassoftheirbrainareamongthemostconsiderableintheanimalworld.Uptothepresentmoment,scientistshavetwodifferentviewsonanimalsintelligence:oneisthatofallanimals,chimpsarethemostintellectualandcapable;anotheristhatchimpsarenomorecapableofstudyingthandolphins,anditisprobablethatdolphinsaremoreintellectualthanchimps.Therefore,somepeopleconsiderdolphinsas“wizardsinthesea”.
Whenmentioningdolphins,peoplewillprobablyspeakhighlyoftheirsupernormalintelligenceandability.Inthataquarium,itiscommonthatdolphinsaregivingawonderfulperformancebyfollowingthetrainersinstructions.Theyseemtobecapableofunderstandingwhatmankindexpressesandtakingactionsaccordingtotheinstructions.Atpresent,themajorityofpeoplemarvelatdolphinssupernormalintelligenceasakindofseaanimal.Buttowhatextentcandolphinsintelligenceandabilityachieve?Itremainstobeprobedandresearched.
②Myfavoriteseaanimalistropicalfish(热带鱼).Ifoundthemonasnorkellingtrip.Iwasattractedbyitscolorfulappearance.Inthehalfanhourstripfromtheshore,Ifoundcoralreefs,tropicalfishandothermarinelife.Excitedly,Iboughtsomefisheshome.Itwasmyfirsttimetoraisetropicalfish.Onemonthagomyfriendtoldmethattropicalfishareeasiertoraisethanthegoldenfish.Herwordsletmethinkofanotherfriendofmine.Heisraisingtropicalfish.Iamfeedingfourcategoriesoftropicalfish.Twoblackmarry,eightpeacocks,anothertwofishes,althoughIdontknowtheirnames,arethemostbeautiful.ThepeacockisthesmallestandisntcolorfulasIhaveseeninotherplacesbefore.Myfriendtoldmetheywillbebeautifulwhentheygrowup.SoIputtheeightpeacockfishintoasmallfishjar.Iobservesthemeverydayandisexpectingthemtobebiggerandmorecolorful.Twoofthefourbigtropicalfisheshavediedincludingthebeautifulone.Perhapsthebeautifulfishslifeisfragile.Ifitistrue,thenIdontexpectthesmallpeacockstoturnbeautiful.Ishouldntbesogreedytowantboth.Thattheyjusthavestronglifeisenoughforme.
2.Theteachershowthepictureofakillerwhaleanddoasmallquizaboutit.
(1)WhatstheChineseandEnglishnameofthiswhale?
虎鲸Killerwhales
(2)CanyoumatchthesewhaleswiththeirChineseandEnglishnames?(Showstudentssomepicturesofdifferentwhales.)
baleenwhale须鲸spermwhale抹香鲸
bluewhale蓝鲸whitewhale白鲸
(3)Whichofthesekindsofwhalescangrowtobethelargest?
Bluewhales蓝鲸(about21-27minlength,100-120tonsinweight)
(4)Humanshavebeenhuntingwhalesformorethan__A__years.
A.2000 B.1000 C.500
(5)Willthekillerwhalesattackpeopleandeatthem? No.
(6)Doesafemalekillerwhalegivebirthtoababywhaleorlayeggs? Givebirthtoababywhale.
(7)Whatdoesanewly-bornbabykillerwhalefeedon?__C__
A.Smallseaanimals.B.Seaplants.C.Itsmothersmilk.
(8)Dothekillersbelongtothefamilyofdolphinsorwhales? Dolphins.
(9)Malekillerwhaleshavealifeexpectancyof__B__years,whilefemalescanliveaslongas__D__years.
A.40-50 B.50-60 C.60-70 D.80-90
(10)Killersarehighlysocialanimalsthattravelingroupscalledpods(群).Podsusuallyconsistof__A__whales.
A.2-50B.20-50C.30-60
(11)Howmanysoundscanakillerwhalemake? 62sounds.
(12)Arekillersendangeredspeciesandinneedofconservation? No.
(13)Thekillerwhalesaresometimescalledthe“__A__ofthesea”becausetheyarebothveryfierce.
A.wolfB.dogC.tiger
?Step2 Pre-reading
1.ReadthewordsinPre-readingonPage19quicklyandfillintheform.
WriterAnoldmancalledClancy
OccupationAwhaler
StyleAnecdotes
TimeAtthebeginningofthe20thcentury
PlaceAustralia
WhathappenedThekillerwhaleshelpedthewhalerscatchabaleenwhale.
?Step3 Skimming
1.Glancethroughthetwoanecdotesanduseonesentencetogetthemainideaofeachanecdote.
Mainideas:
Anecdoteone:Thekillerwhaleshelpedthewhalerstocatchabaleenwhale.
Anecdotetwo:OldTomsavedawhalerJames.
2.Fillintheblankswiththenamesoftherolesinthetext.
(1)______was16yearsofagewhenhewenttoworkatthewhalingstation.
(2)______orderdClancytogototheboatastherewasawhaleoutthereinthebay.
(3)______wasswimmingbytheboatshowingthewhalerstheway.
(4)______toldClancythattheywouldreturnthenextdaytobringinthebodyofthewhale.
(5)______wascarriedbythewavesfurtherandfurtherawayfromthewhalers.
(6)______knewthatOldTomwouldprotectJames.
Suggestedanswers:(1)Clancy (2)George (3)OldTom (4)Jack (5)James (6)Red
?Step4 Scanning
1.Readthesetwoanecdotescarefullyandfindoutsomeverbsorverbphrasestodotheblank-fillingworksheet.
Anecdoteone:
Therewasperfectcooperationbetweenthewhalersandthekillerwhales.
Beforethehunt
Thekillersaction:Threw_itselfout_ofthewaterandthencrashed_downagain.
Swam_bytheboat,showingthewhalerstheway.
Circledbacktotheboat,leadingthewhalerstothehunt.
Thewhalersreaction:Awhaleryelledout.Georgeranahead_of_clancy.Clancyraced_afterhim.
Theyjumped_into_theboatwiththeotherwhalersandheaded_outintothebay.
Duringandafterthehunt
Thekillersaction:Apackofkillersarethrowing_themselvesontopofthewhalesblow-holeto_stopitbreathing;someothersarestoppingitfleeing_outtosea.
Thekillersstartedracing_betweenthewhalersboatandthewhale,justlikeapackofexciteddogs.
Withinamomentortwo,thewhalesbodywasdragged_down_intothedepthsofthesea.
Thewhalersreaction:Themaninthebowoftheboataimedaharpoonatthewhaleandletitgotohitthespot.
Startedturningtheboataroundtogohome.
Anecdotetwo:
ThedangersfacingJames:
(1)Hewaswashed_off_theboatandwascarried_away_byroughwaves.
(2)Therewasasharkoutthere.
ThehelpofferedbyOldTom:
(1)OldTomwouldnt_let_thesharknear.
(2)OldTomfirmlyheldJamesupinthewater.
2.Readingaloudandunderliningexpressions.
Studentsreadthetextaloudtothetapeandunderlinealltheexpressionsinthetext.Putthemdownintotheirnotebooksafterclassashomework.
Suggestedanswers:
Collections:atthetime,witnesssth.withonesowneyesmanytimes,sortoutmyaccommodation,intimetodosth.,crashdown,yellout,aheadof,fleeouttosea,aimat,letsth.go,bedraggedswiftlydownintothedepthsofthesea,inthemeantime,haveagoodfeedonsth.,becarriedfurtherandfurtheraway,befirmlyheldupinthewater
3.Reading,identifyingandsettling.
Studentsskimthetextonceagainandidentifythedifficultsentences.Letthemtryanalyzingthestructuresofthedifficultsentencesanddiscussthemamongtheirgroupmembers.Theymayalsoturntotheteacherforhelp.
...Georgedidntlikebeingkeptwaiting...
...Icouldseeawhalebeingattackedbyapackofaboutsixotherkillers.
Beingbadlywounded,thewhalesoondied.
...Icouldseehewasterrifiedofbeingabandonedbyus.
?Step5 Discussion
Afterthestudentsreadthepassage,askthemtodiscussthefollowingquestionsingroupsandthenreporttotheclass.
1.WhyhasthekillerwhalegotthenameOldTom?
2.Doyoulikekillerwhales?Whyorwhynot?
Suggestedanswers:
1.OldTomisapersonsname.Inmyopinion,thereasonswhythekillerinthetextiscalledsomaybetwo.Foronething,thekillerthatshowedthewhalersthewaytothehuntandsavedJamesmustbeamalekillerwhalebecauseTomisamansname.Foranother,thewhalerscalleditOldTom,justastheywerecallingaman.Thatistosay,thewhalerstreateditastheirdearfriend.Inthemeantime,thekilleritselfmustbeveryfriendlytothewhalersandhelpedthemalotinhuntinginthesea.Inreturn,thekillercangetpartofthebaleenwhaleasitsfood.Sotosomeextent,thewhalersandkillersaredependingoneachother.Theycooperatedwellandlivedinharmonywithoneanother.
2.IlikekillerwhalesbecausewhenJamesfellofftheboat,thekillerwhalenotonlyprotectedhimfrombeingdrownedbutalsowouldntletthesharknear.Theyaresocleverandfriendlytohumanbeings.Whatsmore,theyworkedasateam,whichshouldbelearnedbyuswhenweareworking.
Idontlikethem.Thoughtheyarecleverandfriendlytous,theyaretoofierce.Tomygreatsurprise,theyshouldeatthefleshofanotherwhale.Icouldhardlybelieveit.Ihaveneverheardofoneanimalkillinghisfamiliesandeveneatingtheirmeat.Howpitifulitis!
?Step6 Further-thinking
1.Whatelsedoyouthinkisamazinginthestory?Showyourevidence.
2.Whatisananecdote?
Suggestedanswers:
1.Ithinkitissoamazingthatwehumanbeingsshoulduseoneanimaltoattackorhuntanotheranimalevenhisownfamilymembers,justlikedogsthathelphuntershuntanimals.
Ithinkthatthekillerwillreturnthebodyofthebaleenwhaleinsteadofkeepingitoreatingitupisveryamazing.ButIguessthekillerwhalesarejustfondofthetasteofthebaleenwhaleslipsandtongue.Ortheyjustwanttoshareitwiththewhalersinreturnfortheircooperation.
2.Accordingtothetext,asfarasIamconcerned,ananecdotemustbeanexcitingoramazingstory.
?Step7 Consolidation
Askstudentstoretellthepassagewiththehelpoftheirworksheet.
1.PleaseretelleitherofthetwoanecdotesinthenameofOldTom,thebaleenwhaleorJames.Youranecdoteshouldatleastconsistoftwoparagraphs:
Paragraphone:aboutthewriter,time,placeandwhathappened
Paragraphtwo:detailedinformationabouttheanecdote
Forreference:
InthenameofOldTom
IamOldTom,akillerwhale.IliveinthesoutheasternoceanofAustralia.EnormousasIam,Ineverharmorattackpeople.Instead,Ialwayshelpthewhalerscatchbaleenwhales.Atthebeginningofthe20thcentury,itwasIandmycompanionswhoassistedthewhalersinhuntingahugebaleenwhale.Andlater,IdidsaveJamesfrombeingdrowned.
Onthatday,whenIfoundabaleenwhalenearby,Iquicklythrewmyselfoutofthewaterandcrasheddownagain.Assoonastheysawthisandheadedouttothehunt,Iswambytheboat,showingthemtheway.Usuallyweworkasateam—apackofaboutsixofuskillers.Somethrewourselvesontopofthewhalesblow-holetostopitbreathing.Andthoseothersstoppeditfleeingouttosea.Atlast,wesucceededincatchingit.Inthemeantime,weenjoyedthelipsandtongueofthebaleenwhale,leavingtherestofittothewhalersthenextday.
Oneday,Jameswaswashedofftheboat.Theseawasrough.Thewaveswerecarryinghimfurtherandfurtheraway.Worsestill,Isawasharkswimmingaround.FromJamessface,Icouldseehewasterrifiedofbeingabandonedbyothersandattackedbytheshark.ButIwouldntletthesharknear.Whentheyapproachedhim,Ihadbeenholdinghimupinthewaterforhalfanhour.
Idohopeyoucouldwitnessthemwithyoureyes.Andmostimportantly,youshouldlearnfromus—“workasateam”!
Inthenameofthebaleenwhale
Iwasapitifulbaleenwhale.IoncelivedinthesoutheasternoceanofAustralia.Atthebeginningofthe20thcentury,amisfortunedidfalluponme.Tomygreatsorrow,Iwascorneredandkilledbythewhalerswiththehelpofanotherkindofwhalecalledkillerwhales.
Onthatday,IwasfoundbyakillerwhalecalledOldTomnearby.Hequicklythrewhimselfoutofthewaterandcrasheddownagain.Assoonasthewhalerssawthisandheadedouttothehunt,heswambytheboat,showingthemtheway.Usuallythekillersworkasateam—apackofaboutsixofthem.Somethrewthemselvesontopofmyblow-holetostopmebreathing.Andthoseothersstoppedmefleeingouttosea.Atlast,Iwaswornoutandhadnoluck.Iwasbadlywoundedbyaharpoon.Ididnothingwrong.Whydidtheywanttokillme?Later,Iwasdraggeddownintothedepthsofthesea,havinghadmylipsandtongueeaten.Iwassentbacktothewhalersthenextday.Ireallyhatedthekillers.Iftheyhadnthelpedthewhalers,Icouldhavefledouttoseatoenjoymyrestlife.
InthenameofJames
IamJames,awhaler.IliveonthesoutheasterncoastofAustralia.Atthebeginningofthe20thcentury,IwassavedbyOldTom,akillerwhale.
Believeitornot,thekillerwhalescannotonlyhelpushuntbutalsosavepeoplewhentheyareindanger.Oneday,OldTomfoundabaleenwhalenearby,itquicklythrewitselfoutofthewaterandcrasheddownagain.Assoonaswesawthisandheadedouttothehunt,itswambytheboat,showingustheway.Usuallythekillersworkasateam—apackofaboutsixofthem.Somethrewthemselvesontopofthebaleenwhalesblow-holetostopitbreathing.Andthoseothersstoppeditfleeingouttosea.Atlast,wesucceededincatchingit.Inthemeantime,thekillersenjoyedthelipsandtongueofthebaleenwhale,leavingtherestofittousthenextday.
Anotherday,Iwaswashedofftheboat.Theseawasrough.Thewaveswerecarryingmefurtherandfurtheraway.Tomakemattersworse,Isawasharkswimmingaround.Iwasterrifiedofbeingabandonedbyothersandattackedbytheshark.Buttomysurprise,OldTomwouldntletthesharknear.Whenmycompanionsapproachedme,IhadbeenheldupinthewaterbyOldTomforhalfanhour.
Thisexperienceleftadeepimpressiononme.IreallyappreciatedOldTom.Itwasitthatgavemeasecondlife.
?Step8 Debate
ThelastwhalingstationinAustraliaclosedin1978.Whalesarenowanendangeredspeciesandprotectedbyaninternationalban,butsomecountriesopposetheban.Ingroupsdiscussthereasonsforandagainstbanningwhaling.
?Step9 Homework
1.Writedowntheusefulnewwordsandexpressions,thenlearnthembyheart.
2.WritedownananecdoteinthenameofOldTom,thebaleenwhaleorJames.
备课资料
PhysicalDescription
Thekillerwhale,ororca,isthelargestmemberofthedolphinfamily.Killerwhalesarelargeandrobustwithabluntheadandreducedbeak.Withtheirstrikingpigmentation,theyarenotoftenconfusedwithotherspeciesintheirnaturalsetting.Orcasarejetblackwithawhitepatchbehindandabovetheeyes.Thelowerjawandthroatarealsowhite,contiguouswithawhitebellypatchthatextendsbacktothegenitalregion.Theundersidesoftheflukesarewhiteandwhitelobesextendupwardsfromthewhitebellytobehindthedorsalfin.Agreysaddlepatchisfoundbehindthedorsalfin,theshapeofwhichisuniquetoindividualwhales.Thetalldorsalfinofmatureanimals,especiallymales,canreachupto1.8meters(5.9feet).Malesreach8.5meters(28feet)inlength,whilefemalesreach6.7meters(22feet).
NaturalHistory
Killerwhalesareoneofthemostcosmopolitanspeciesofwhales,withadistributionthatspanstropicaloceansandarcticseas.Theyarehighlysocialandformstrongandpersistentsocialbondswiththeirpodmembers.Podsaremadeupofextendedfamilymembersand2ormorepodsmaycometogetherforshortperiodstomate.Theworldskillerwhalepopulationseemstoconsistofsubpopulationsadaptedtolivewithinthespecializednicheoftheirenvironment.Apodsmovementstendstofollowthoseoftheirintendedpreywhich,dependingonlocation,mayincludesalmonherring,baleenwhales,penguinsandseals.
Status
InCanada,killerwhalesarelistedasthreatenedbytheCommitteeontheStatusofEndangeredWildlife(COSEWIC)andareprotectedunderthenewfederalSpeciesatRiskAct(SARA).Otherpopulationsworldwidemaybeprotectedunderspecificnationallegislation.
ThreatstotheSpecies
Althoughtheglobalpopulationofkillerwhalesisnotendangered,differentregionalpopulationsaredepleted.ResidentandtransientpopulationsoffthecoastofVancouver,CanadaandWashingtonState,U.S.,weredepletedbythelivecapturefisheryforaquariathatoccurredbeforescientistsknewhowmanykillerwhalesexistedinthepopulation.Todaythesepopulationsnumberonlyafewhundredwhalesandarethreatenedbypollution,heavyshiptraffic,andpossiblyreducedprey.Becauseofthekillerwhalespopularity,thereareconcernsthatintensivewhalewatchingoperationsmaydrivewhalesfromtheirpreferredhabitat.Aswell,noise-makingdevicesattachedtosalmoncagestoscareoffpredatorsmayalsoforcewhalesoutoftheirpreferredhabitat,affectingtheirabilitytofeed.SomeorcapopulationsarealsohuntedinJapan,Indonesia,GreenlandandtheWestIndies.
外形特征
虎鲸是一种大型齿鲸,身长为8~10米,体重9吨左右,背呈黑色,腹为灰白色,有一个尖尖的背鳍,背鳍弯曲长达1米,嘴巴细长,牙齿锋利,性情凶猛,食肉动物,善于进攻猎物,是企鹅、海豹等动物的天敌。有时它们还袭击其他鲸类,甚至是大白鲨,可称得上是海上霸王。
寿命:雄性:50~60年;雌性:80~90年,甚至100年
雌雄虎鲸外观区别(上雄下雌)
虎鲸的体型极为粗壮,是海豚科中体型最大的物种。头部呈圆锥状,没有突出的嘴喙。大而高耸的背鳍位于背部中央,其形状有高度变异性,雌鲸与未成年虎鲸的背鳍呈镰刀形,而成年雄鲸则多半如棘刺般直立,高度约1至1.8米。胸鳍大而宽阔,大致呈圆形,这点与大多数海豚科成员的典型镰刀状背鳍不同。上、下颚各有10至14对大而尖锐的牙齿作为武器,每颗牙大概有8厘米。在海湾的浅水地带,它还喜欢用尾巴去钩拉海藻,发出“呼呼”的声音,不久,浑身就披满了半透明的海草。
虎鲸的体色图样主要由黑与白这两种对比分明的色彩组成,位于身体腹面的白色区域自下颚往后延伸至肛门处,在全黑的胸鳍之间变得狭窄,到了肚脐后方产生分歧,尾鳍腹面亦为白色。背部与体侧皆为黑色,但在生殖裂附近的侧腹处有白色斑块,眼睛斜后方亦有明显的椭圆形白斑。在背鳍后方有呈灰至白色的马鞍状斑纹。
习性
虎鲸时常会有跃身击浪、浮窥等行为,或是以尾鳍或胸鳍拍击水面。虎鲸的泳速最快可达时速55千米,可闭气17分钟左右。当周遭空气凉爽时,通常可看见它们低矮而呈树枝状的喷气。它们对船只的反应多样,冷漠忽视或是充满好奇心都有可能。偶尔会集体搁浅,群体有时会被困在潮池或海湾中。在北极与南极海域,因为风吹而快速产生的浮冰对虎鲸而言是一大麻烦,有时会因此迫使它们停留于水面开阔的小水域里相当长的时间。
虎鲸喜欢群居的生活,有2~3只的小群,也有40~50只的大群,每天总有2~3个小时静静地待在水的表层,因为肺部充满了足够的空气,所以能够安然地漂浮在海面上,露出巨大的背鳍。群体成员间的胸鳍经常保持接触,显得亲热和团结。如果群体中有成员受伤,或者发生意外失去了知觉,其他成员就会前来帮助,用身体或头部连顶带托,使其能够继续漂浮在海面上,就是在睡觉时也扎成一堆,这是为了互相照应,并保持一定程度的清醒。它们在一起旅行,用食,以种群为社会组织,在广大的家庭中休息,互相依靠着生存长大。
食性
虽然它的牙齿非常坚硬,但却不如鲨鱼的牙齿那样锋利,因此主要用于摄取而不是咀嚼,而被它叼住的食物都是整个吞下的。虎鲸的食物多样,由小型结群鱼类、鱿鱼(枪乌贼),一直到大型须鲸与抹香鲸都有可能成为它们的猎物;其他的如海豹等鳍脚类动物、海龟、海豚、海狗、海獭、海牛、儒艮、鲨鱼、魟等,甚至还有鹿与麋鹿,似乎是趁它们游泳横渡水道时伺机捕食。甚至会利用涨潮冲到海岸边,捕捉来不及逃走的海豹、企鹅。各群似乎有自己偏好的食物种类,例如某些族群主要以鲑鱼、鲔鱼、或鲱鱼等鱼类为主要食物,某些群则会巡视鳍脚类的登陆地寻找猎物,或跟随迁徙中的鲸群,有如狼群追踪北美驯鹿的情景。虎鲸显然需要合作以袭击并制服大型猎物,但它们也会合力将鱼群集中成一个大球,然后轮流钻入取食。虎鲸也会偷吃延绳钓渔船上钩的鱼获,或吃食渔民丢弃的下杂鱼等。它们似乎会选择性的咬食须鲸的舌头。其猎物可能深受对虎鲸的恐惧所影响,当虎鲸出现时鳍脚类会逃往陆地或冰上,鲸豚则会游入浅水域或藏匿于浮冰的裂隙间。
高中物理粤教版(选修3-1)
第一章《电场》教学设计
一、教学内容分析
本章的概念比较多,应引导学生抓住力与能这条主线,以把整章的知识联系起来,并重视电场与其他物理知识的联系,巧用类比,加深理解。另外,受力分析是解题的基础,应强调学生要画受力图。本章知识的命题频率较高且有相当难度的集中在电场力做功与电势能变化、带电粒子在电场中的运动这两个知识点上,尤其在与力学和磁场等内容综合时,巧妙地把电场概念、磁场力、牛顿运动定律和功能原理等联系在一起,对学生能力有较大要求。
二、学情分析
学生通过新课的学习,已经本章内容有一定的认识,但是由于本章涉及的概念较多,也比较抽象,因此在复习时,要对主要知识点进行疏理,并要针对学生不理解的、容易混淆的概念,运用类比的方法帮助学生理解及区分,同时按学生的实际水平,选择难度适当并有代表性的题目进行分析并加以练习强化。
三、教学目标:
(一)知识目标
1.加深理解电场强度、电势、电势差、电势能、电容等重点概念。
2.在熟练掌握上述概念的基础上,能够分析和解决一些物理问题。
3.通过复习,培养学生归纳知识和进一步运用知识的能力,学习一定的研究问题的科学方法。
(二)过程与方法
1、列表疏理重要的知识点
2、运用类比法加深对概念的理解
3、利用学案导学,讲解与练习相结合
(三)情感态度与价值观
1、通过类比各物理概念的联系与区别,让学生体会物理概念的严谨性,不同物理知识之间紧密联系的奥妙,培养在理解物理量时举一反三的能力。
2、通过典型综合题的分析,让学生体会把力学与电学知识成功综合运用的快乐。
四、教学重、难点:加深理解电场强度、电势、电势差、电势能、电容等重点概念;电场力做功与电势能变化的关系,带电粒子在电场中的运动。
五、教学策略:
对重要知识点建立框图,力求简明扼要;疏理知识点时把抽象概念多与学生相对熟悉的知识进行类比,帮助学生加深理解;利用学案导学,在复习中注意讲练结合。
六、教具:多媒体课件,学案,
七、教学过程:
教学环节教师活动学生活动教学目的
(一)梳理基础知识
本章的主要内容可分为下面几大块:
一、静电、静电力(三种起电方法,两个规律:电荷守恒定律、库仑定律)
二、电场的研究(两种性质和相互关系)
1、两种性质:力的性质及能的性质
2、两种相互关系:电场力做功与电势能变化的关系、电场强度与电势差的关系
三、电场的应用(示波器和电容器)
1、示波器:带电粒子在电场中的加速和偏转
2、电容器:电容器的工作过程与动态分析
(用PPT演示基础知识的填空题,让学生边回答,再对重要的知识难点加以解释)先利用学案中的框图,对本章知识要点进行梳理,然后解答PPT中提出的问题。对主要知识点进行梳理,建立知识结构
(二)难点辨析,专项练习及讲解
(三)综合题分析及强化练习
(四)小结、作业布置一、电场强度E(矢量)的理解.
电场强度E是电场本身的一种特性,与检验电荷存在与否无关.E是矢量.要区别公式E=F/q(定义式)、E=kQ/r2(点电荷电场)、E=U/d(匀强电场)的物理意义和适用范围.提出问题:E既然是矢量,那么如何比较电场中任两点的场强大小和方向呢?
启发学生用多种方法判断.然后将学生回答内容归纳.可能方法有:
(1)判断电场强度大小的方法.
①根据定义式E=F/q;
②点电荷电场,E=kQ/r2;
③匀强电场,场强处处相等,且满足E=U/d;
④电场线密(疏)处场强大(小).
(2)判断电场强度方向的方法.
①正电荷所受电场力的方向即是该点的场强方向;
②电场线上每一点的切线方向即是该点的场强方向;
③电势降低最快的方向就是场强的方向.
教师巡查学生练习的情况,把学生解答中出现的类似错误及典型错误用投影机演示,作有针对性的讲解。
二、关于电势及电势能
电势Φ是电场本身的一种特性,与检验电荷存在与否无关.Φ是标量.规定:无限远处的电势为零.电势的正负和大小是相对的,电场中任两点间电势差U的值是绝对的.
电势能是电荷和电场所组成的系统共有的.规定:无限远处的电势能为零.电势能的正负和大小是相对的,电势能的差值是绝对的.提出的问题:
(1)如何判断电势的高低?
启发学生用多种方法判断.然后将学生回答内容归纳可能方法有:
①根据电势的定义式Φ=W/q,将+q从无穷远处移至+Q电场中的某点,外力克服电场力做功越多,则该点的电势越高;
②将q、εP带符号代入Φ=εP/q计算,若Φ>0(<0),则电势变高(低);
③根据电场线方向,顺(逆)着电场线方向,电势越来越低(高);
④根据电势差,若UAB>0(<0),则ΦA>ΦB(ΦA<ΦB);
⑤根据场强方向,场强方向即为电势降低最快的方向.
(2)怎样比较电势能的多少?
启发学生用多种方法判断,将学生回答归纳,可能方法有:
①可根据电场力做功的正负判断,若电场力对移动电荷做正(负)功,则电势能减少(增加);
②将q、Φ带符号代入εP=qΦ计算,若εP>0(<0),则电势能增加(减少).
教师巡查学生练习的情况,把学生解答中出现的类似错误及典型错误用投影机演示,作有针对性的讲解。
针对静电力、电场的研究及电场的应用(带电粒子在电场中的运动及电容器的动态分析)等三大块内容进行相关典型例题的分析及强化练习:
先用PPT展示相应例题,先让学生思考,再点拨及启发。然后做学案上的强化练习,教师巡查,然后就学生解答中出现的问题进行分析。
教师小结:本章的学习方法:1、抓基础,善用类比加强对概念的理解;2、抓主线,抓住电场的力的性质及能的性质这条主线;
3、注意考虑利用功能关系解题,分析带电粒子在电场中的运动时,要画受力图
作业:完成导学案上剩下的题目;再次复习辅助教材中关于本章的主要概念,加深理解。思考并讨论、回答相关问题,有必要时要做笔记再完成学案中相关的专项练习
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