Unit7Howdothingschange？Extend（课件）-沪教版英语四年级下册

Unit7Howdothingschange?ExtendSolid(Ice)Liquid(Water)Gas(Vapor)Contents01.Warm-up&Lead-in02.Whatisourworldmadeof?(Solids,Liquids,Gases)03.Howdothingschange?(Watercycle)04.Think&SummaryWarm-up&Lead-inSolid(Ice)Liquid(Water)Gas(Steam)Question:Lookatthepictures.Whatarethey?Whatstatearetheyin?Whatisourworldmadeof?CoreQuestionWhatisourworldmadeof?AnswerEverythingismadeofsolids,liquids,orgases.SolidsLiquidsGasesSolidsDefinition:Solidshaveafixedshapeandsize.IceAsolidformofwater,maintainsshapeevenindifferentcontainers.MetalIronblocksarerigidsolidswithadefiniteshapeandvolume.KeyTakeaway:Solidsdonotchangetheirshapeeasily.MoreSolidsQuestion:Whatotherthingsaresolids?StoneBookTableKeyPoint:Alltheseexampleshaveafixedshapeanddonotflowlikeliquids.LiquidsDefinition:Liquidscanflowandtaketheshapeoftheircontainer.WaterAcommonliquidthatisessentialforlife.Itflowseasilyandconformstotheshapeofitsglass.MilkAnotherexampleofaliquid.Itisopaqueandalsotakestheshapeofthecontaineritisin.KeyTakeaway:Liquidshaveadefinitevolumebutnofixedshape.MoreLiquidsQuestion:Whatotherthingsareliquids?JuiceOilColaAlltheseexamplesshowthatliquidscanflowandtaketheshapeoftheircontainer.GasesDefinitionGasesareallaroundus,butwecan'talwaysseethem.Theyfillthespacetheyarein.ExamplesAirandsteamaregases.Webreatheaireveryday,andsteamrisesfromboilingwater.MoreGasesQuestion:Whatotherthingsaregases?BalloonGasTheairinsideaballoonisagasthatkeepsitfloating.CarbonDioxideDryiceissolidcarbondioxide,whichturnsintogas.KeyTakeaway:Gasesareallaroundus,eveninformswemightnotexpectlikedryice!Butthingschange.KeySentence:Butthingschange.Meaning:Thestateofmattercanchange.ScienceInsight:Waterisagreatexample!Itcanchangefromsolid(ice)toliquid(water)andthentogas(steam),dependingontemperature.Howdothingschange?(Melting)Process:Melting(fromsolidtoliquid)Theiceisasolid.Nowit'smelting.It'schangingintoaliquid.SolidLiquidHowdothingschange?(Freezing)Process:Freezing(fromliquidtosolid)Sentence:Thewaterisaliquid.Nowit'sfreezing.It'schangingintoasolid.KeyConcept:Freezingistheprocesswhereasubstancechangesitsstatefromliquidtosolidduetoadecreaseintemperature.Howdothingschange?(Boiling)Process:BoilingAchangefromliquidtogasduetoheating.Observation"Thewaterisaliquid.Nowit'sboiling.It'schangingintoagas."KeyConcept:Whenwaterboils,itturnsintosteam(gas).Thisisaphysicalchange.TheWaterCycleConceptThewatercycleshowshowwaterchangesitsstate(solid,liquid,gas)continuouslyinnaturethroughaseriesofprocesses.KeyProcessEvaporationHeating&BoilingCondensationCooling&CloudsPrecipitationRain/SnowCycleCompletion:Thewaterreturnstotheoceanorground,andthecyclerepeatsendlessly.ThinkQ1:Whendoeswaterchangeintoagas?A:Whenitboilsorgetshot.Q2:Whendoesitchangeintoasolid?A:Whenitfreezesorgetscold.KeyConcept:Waterchangesitsstate(solid/liquid/gas)dependingontemperature.Practice:MatchMatchtheprocesstothepicture:Meltingsolid→liquidIceturnsintowaterFreezingliquid→solidWaterturnsintoiceBoilingliquid→gasWaterturnsintosteamPractice:FillintheblanksFillintheblankswiththecorrectwords:1.Iceisa______.2.Waterisa______.3.Steamisa______.4.Whenicegetswarm,it______.5.Whenwatergetscold,it______.6.Whenwatergetshot,it______.WordBanksolidliquidgasmeltsfreezesboilsSummaryCoreVocabularysolid,liquid,gas,melt,freeze,boilCoreConceptsEverythingismadeofsolids,liquids,orgases.Mattercanchang