选修七UnitUndertheseaPeriod7.doc

Period 7Listening Task，Talking and WritingTeachingaims1Studentswillbeabletofindoutthereasonswhythepopulationofsharksdecreasessharply.2Studentswillbeabletoexpressopinionswiththepoliteexpressionslike：Idontthinkitiswiseto.Itwouldbebetterifwe.Itisagoodideato.Isupposeitisright.Iwonderif.3Studentswillbeabletopersuadethelocalgovernmenttoprotectwildlifeinapoliteway.TeachingproceduresStep1BeforelisteningShowstudentsapictureofsharkandtellthemafactthatsharkpopulationsaredecreasingrapidly.Step2DuringlisteningTask1：TellstudentsJordonDaviesisinterviewingthesharkexpertDonJamesaboutthesharkssituation.Firstreadthestatementsbelow.Thenlistenandnumberthesestatementsintheorderthattheyhearthem.Sharkpopulationsgrowataveryslowrate.Alotarekilledbecauseofmodernfishingtechnology.Governmentsshouldtakeactionsothatthefishingofsharksissloweddown.Sharkattacksgetalotofattentioninthenews.Sharkpopulationsaredecreasingataseriousrate.Somespeciesneedtobeprotected.Thechanceofbeingbittenbyasharkisactuallyverysmall.Millionsofsharksarekilledeachyear.Keys：theorder：74815623Task2：Listenagainandanswerthefollowingquestions：1Shouldpeoplebeafraidofswimminginthesea?2Howmanypeoplearekilledbysharkseachyear?3Dosharksorpeopleneedtobeprotected？Why?4Whyaresomanysharksbeingkilled?5Whydoesthesharksbiologyaffectsharkpopulations？Completethesentencesblow.A：Ageforreproducingyoung_B：Timefortheyoungtodevelop_C：Numberofyoung_6Howlonghavesharkspeciesbeeninexistence?7WhatdoesDonthinkwillhappenifwedontslowdownthefishingofsharks?Suggestedanswers：1No.2Onlyafew.3Sharksneedtobeprotectedasmillionsarekilledeachyearbyhumanbeings，whereasonlyafewhumanbeingsarekilledeachyearbysharks.4Sometimestheyarekilledbyaccidentandsometimesonpurpose.Forexample，sharkfinsoupisadelicacyinsomeAsiancountries.515years；14months；79.6400millionyears.7Donthinksthatmanysharkspecieswillnotbeabletosurvive.Step3Postlistening(talking)Askstudentstomakeupadialogueaccordingtothesituationbelow.SupposeyouwereacitizeninacoastalcityinChina，sharkhuntisaseriousprobleminyourprovince.Trytopersuadethelocalgovernmenttotakeactiontoprotectwildlifeinapolitewaywiththehelpofthefollowingexpressions：Idontthinkitiswiseto.Itwouldbebetterifwe.Itisagood/wiseideato.Isupposeitisright.Iwonderif.Whynot.Wedbetter.Step4HomeworkWriteapersuasivelettertothelocalgovernmenttocontroltheimproperhunts.1KillerWhalesCommonname：KillerWhaleScientificname：OrcinusorcaSize：Femalescanreachlengthsupto24feetandweighbetween3000to8000lb.Malescanreachlengthsupto27feetandcanweighupto12000lb.Calvesareabout8feetlongand300to400poundsatbirth.Wherearetheyfound?FromtheNorthPoletotheSouthPolefromtheIndianOceantotheAtlantic，killerwhalesarefoundinalloceansoftheworld.Whatdotheyeat?Howdotheygetanamelike“killer whale”？Killerwhalesareoneofthetoppredatorsinthesea.Asagroup，killerwhalesareknowntoeatfish，squid，seals，sealions，penguins，evenotherwhales.But，keepinmind，itwouldbedifficultforakillerwhaleoffthecoastofCaliforniatoeatapenguin.Killerwhaleseatthefood(orprey)thatsavailabletothem.Forexample，akillerwhalethatlivesinthenorthernPacificcanhuntharborseals，Californiasealions，andavarietyoffish.AkillerwhaleintheAntarcticcouldfindWeddellseals，leopardseals，andpenguins!ResearchersstudyingkillerwhalesintheNorthwestPacifichavefoundthatsomepodsfeedprimarilyonfishandothersseemtoprefermarinemammals.Akillerwhaleusesitssharpteethtocatchitsprey.KillerWhaleHighlights：Scientistshavedeterminedthatkillerwhalescanliveamaximumof35years.How？Bylookingatacrosssectionofakillerwhalestooth.Killerwhales，likeothermarinemammals，produceaperiodicgrowthlayerontheteeth.Bycountingtheselayers，scientistscanestimatetheanimalsage.Youcantellanadultmalefromanadultfemalebytheshapeoftheirdorsalfin.Thisisamale(photobelow)，howdoweknow？Amalesfinisverytall(upto6feettall)andtriangularshaped.Afemaleisshorter(3feet)andcurvesbacktowardthedorsalfin(seethepictureofthemother/calfabove)2Theearthsoceanscanreachdepthsofupto11000meters.ThatisdeepenoughtocoverMt.Qomolangma！Theoceansareincrediblylargeandcontainseveraldifferenthabitats.Tomakeiteasiertodescribethevariouspartsoftheoceans，marinescientistsusuallydividetheoceansintofivezones.Eachzoneisdifferentmainlyasaresultofhowmuchsunlightreachesit.Mostofthelifeintheoceancanbefoundinthefirstzone，whichbeginsatthesurfaceandgoesdownabout200meters.Becausethereissunlightatthislevel，plantsareabletogrow.Marineanimalssuchasdolphins，sharks，seaturtlesandsealions，andofcourseavarietyoffish，liveinthesunlitpartoftheocean.Itisdifficulttohidefromotheranimalsinthisarea.Thesecondzonestartsat200metersandgoesdowntoabout1000meters.Somesunlightcanreachthislevel，butitisnotenoughforplantstogrow.Becausethiszoneisrelativelydark，manyofthecreaturesthatlivehereareabletomakelightwiththeirbody.Thelightfromtheseanimalsmakesthewaterlooklikeaskywithmovingstarsinit.Thethirdzoneoftheoceanisdark.Thisplace，about3000metersdeep，maynotseemalikelyhabitat，buttherearemorecreaturesherethanonemightthink.Mostoftheanimalsthatlivehereareblackorredbecauseofthelackoflight.Below4000meters，thetemperatureisnearfreezingandthereisnolightatall.Infact，thezoneissodarkandemptythatscientistsnamedthiszoneaftertheGreekwordfor“no bottom”Thereisnotmuchlifetobefoundinthiscoldandunpleasantpartoftheocean，butsomesmallcreaturesstillmanagetosurviveheredespitethehighwaterpressure.Theverydeepestpartoftheoceanisfound2000metersfurtherdown.Atthisdepth，thewaterpressureisextremelyhighandlifeisverydif