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• [3]SB3.1Thestudentdemonstratesanunderstandingoftheinteractionsbetweenmatterandenergyand the effects of these interactions on systems by recognizing that temperature changes cause chang-esinphasesofsubstances(e.g.,icechangingtoliquid,waterchangingtowatervapor,andviceversa).
Vocabulary:Permafrost – permanently frozen subsoil, occurring throughout the polar regions and locally in perennially frigid areas.
Whole Picture:Permafrost is soil, semi-decomposed vegetation, a dead wooly mammoth buried in the ground, or any other material that has remained frozen for more than two years. Permafrost is a function of frigid win-ters or cold periods powerful enough to outweigh the thawing power of summers. Permafrost forms on Earthincoldplaceswhenthemeanannualtemperatureiscloseto27˚F(-3˚C)orbelow. MuchofthepermafrostinAlaskawasestablishedduringamuchcolderperiodmorethan20,000thou-sandsofyearsago,whenairtemperaturesweresocoldtheypenetrateddeepintosoil,suckingoutheatyearafteryearandleavingplaces,suchasAlaska’sNorthSlope,withfrozensoilseveralthou-sands of feet deep. People have paid attention to permafrost because of how it affects our buildings, roadways, and pipe-lineswhenitthawsandcausesthegroundtoslump.Whenkeptfrozen,permafrostprovidesastrongfoundation,butwhenice-richpermafrostthaws,settlingoccurs,bucklingroadwaysandforcingpeopleto repair unstable foundations.
3. Explainliquidschangebasedontheshapeofthecontainertheyarein.Showstudentshowtheshapeoftheliquidchangesindifferentcontainersbypouringamoderateamountofliquid(water)intothreeorfourdifferentlyshapedcontainers.Makesurestudentsunderstandthattheamountofliquidhasn’tchanged,onlyitsshape.Ifnecessary,marktheleveloftheliquidintheoriginalcontainerandpourtheliquidbackintoitsoriginalcontainerbetweeneachothercontainertodemonstratethatitsvolumehas not changed.
4. Askstudentswhatwillmakeasolidmelt.Listanswersontheboardorpaper.Explainheatiswhatmakesasolidmelt.Thiscanbedemonstratedbyplacingiceonaplateunderalampornearaheatsourceandinstructingstudentstowatchitmelt for30minutes,checkingitevery10minutes.Askstudents what other solids melt when they are heated. (butter, chocolate, etc.).Iftimeandresourcesallow, demonstrate melting with other substances.
6. Askstudentstodefinepermafrost. Ifnecessary,explainthat it ispermanently frozenground.Thismeansthegroundneverthawsormelts,eveninthesummer.Askstudentshowfrozengrounddiffersfrom non-frozen ground. (Frozen ground is hard, cold and can be used to keep things cold; non-fro-zen ground can be softer, warmer, and may be wet.)
7. Dividestudentsintosmallgroups.Filltwopapercupsforeachgroupwithsoilandaddasmall,butequalamountofwatertoeachcup.Askstudentstodescribethesoilandwatermixture.Askstudentstopredictwhatwillhappentothemixtureifitisplacedinthefreezer(ActivityProcedure9).Listallstudent ideas on the board or chart paper.
8. Place one cup from each group in the freezer.
Day 2
9. Remindstudentsoftheirpredictions.Removethesoilandwatermixturefromthefreezer.DistributeSTUDENTWORKSHEET:“Chilling”andaskstudentstodrawapictureofboththefrozenandnon-frozen mixtures and write about what they see. As a class, discuss student observations and remind students that permafrost is permanently frozen ground, or ground that is always frozen, even in the summer.
Extension Ideas: (1)Invitestudentstocreateacollageandwriteapoemtoaccompanyitin“ISpy”fashion.Providemagazinesandscissors,orpre-cutpicturesofliquidsandsolids,constructionpaperandglue for thecollage.Afterstudentshavefinishedtheircollage, instruct themtowriteapoem.Olderstudentscancreateariddle,suchasfororangejuiceandsocks,“Ispyaliquidthat’sorangeandsweetandasolidthat’ssmellslikemybrother’sfeet.”Youngerstudentsmayidentifytheliquidsandsolidsintheircollagewithouttheriddle,suchas“Ispysomejuice,arake,andabrush,agoose,a cake, and a plate of mush.” If appropriate, introduce or encourage rhyming. ([3-4] SB1.1) (2)Putsmallquantitiesofdifferentsubstances(e.g.,chocolate,wax,butter,icecube,cheese)intosmallplasticorfoilcontainers(suchastarttins)andstandthemorfloattheminhotwater.Askstu-dentstoobservethechanges.Dotheyallmelt?Whyorwhynot?Removethecontainersandplacethemincoldwateroronabedoficeandaskstudentstoobservethemsolidifying.Olderchildrencaninvestigatethatmaterialsmeltatdifferenttemperaturesortimehowlongittakesforeachsubstanceto melt, collecting and graphing their data. ([3-4] SB3.1)