{{B}}Set4CourseInformation{{/B}}{{B}}Narrator{{/B}}Listentoalecturetalkaboutbassinbusinessclass.

The History of the Virginia Colony As the 15th century came to close, the domination of Spanish power in Europe began to wane and was gradually replaced by an emerging naval power, that of England. Queen Elizabeth had promised its subject immeasurable wealth should they bring the British Empire what the Conquistadores had in their epoch of glory, namely the domination of the New World. Early attempts of colonizing North America had failed largely due to the bloody resistance mounted by the Native tribes, as well as an adverse climate. In spite of such obstacles, however, the English would not be detered. Their hardy spirit and industriousness launched the most successful colonizing venture yet. The first such attempt to settle down on the North American continent occurred in 1607, when the London Virginia joint stock Company subsidized the formation of Jamestown on the mouth of the Chesapeake River. The settlement, named in honor of the newly enthroned monarch James l, was founded in the wake of the Popham colonial disaster which had to be abandoned later that same year. The London Virginia Company, who had sponsored Popham, had now set its eyes on the fertile region of the Chesapeake discovered by the conquistador Lucas Vasquez de Ayllon. It hoped to recover its losses by discovering precisely the vast quantities of gold which had thus eluded the Spanish. It was precisely this greedy attempt to corner all the wealth which put Jamestown in peril. The first colonists there were namely ruthless gold seekers comprised of jewelers, silversmiths and aristocrats who started to mine the land for precious metals. This group of people subsisted by means of trading with the local Powhatan Indians, and had no expertise in tilling the land. As a consequence, when the first drought spell hit the land, the English colonists found themselves in dire straits . The Natives were no longer willing to share their meager food sources with strangers, and bereft of nourishment, the settlers turned to cannibalism for survival. The chaos was exacerbated by the lack of a cohesive social structure and a sense of community to which the colonists could turn to. Those who had come to Jamestown were venal profiteers who felt little attachment for a communal lifestyle. Moreover, they were all male with no families to look after and thus no incentive to build one. It was the effort of John Smith who saved the colony from collapse. [■] He managed to rally the men behind him and motivate them to work the land to yield crops for nourishment. [■] He also befriended chief Powhatan"s daughter, the legendary Pocahontas, who was able to supply the colony with food. [■] in the years to come, it would become as profitable as one could have wanted. [■] The turning point in the history of the Virginia colony was the discovery of another type of wealth. In the conspicuous absence of gold, the colonists had to resort to different means to turn a dollar. Hence, in 1612, John Rolfe, one of the leading man in town, turned to the cultivation of tobacco as cash crop. The English settlers had become adept at planting tobacco after picking up the trade from their Powhatan allies. With smoking becoming increasingly popular in Europe, the Virginia colonists soon found themselves involved in quite a lucrative and lively trade, which would become the trademark of Virginia commerce in the 18th century. A new type of immigrants docked on the banks of the Chesapeake River during the 18th century. Since tobacco was labor-intensive, early colonists had to resort to the employment of indentured servants to cultivate their large plantation fields. Some of these indentured workers were Africans who would sign on as laborers for a certain amount of time. At the end of their indenture, they would either regain their freedom or sign on for yet another term. The fiercely competitive environment and the white domination, however, constrained Africans to remain indentured for a lifetime and eventually turned them into slaves. The main bulk of indentured slaves came nonetheless from mother England itself. The English Civil War had caused profound disruptions in the social structure of the time. Medieval landowners evicted their tenants from their newly privatized manors, and this new uprooted poor class emigrated to the Virginia territory in search of employment. Similarly, Cromwell"s Protectorate and the strictly enforced Puritan lifestyle had many middle-class Catholics settle in Virginia. As a result, the Jamestown colony underwent a social upheaval, with the old gentry of tobacco planters controlling land and labor. The short-lived Bacon"s Rebellion in 1676 allowed the lower classes to gain the upper hand, but the arrival of English ships soon ended that situation and reinstated the absolute domination of aristocratic landowners. Glossary Conquistador: one of the Spanish conquerors of Mexico and Peru in the 16th century profiteer: a person who seeks or exacts exorbitant profits reinstate: put back or establish again as in a former position or state

TOEFLReadingPassage2America'sWesternMigration1.AfterAmericadeclaredindependencein1776,itscitizensbeganmigratingfromtheoriginalcoloniesalongtheAtlanticcoast,crossingtheAppalachianMountainsandheadingwest.By1800,tradingcentershadbeenestablishedfromOhiotoAlabamaandpioneerswerealreadymakingtheirwaytowardstheMississippiRiver.WiththeLouisianaPurchaseof1803andfurtherlandacquisitions,thefrontieroftheAmericannationwascontinuallypushedwestward,andgroupsofsettlerswereneverfarbehind.2.ThistremendousmigrationwascarriedoutbyindividualswhochosetoleavetherelativesafetyoftheEastandventureintounknownterritories.Theyfollowedcommontrails,theearliestofwhichledtoplaceslikeMissouri,Kansas,andNebraska.After1840,othersintotheFarWestwereopenedandsawsteadilyincreasingtraffic.Thepeoplewhoundertooksuchjourneysweremotivatedbyavarietyoffactors.EarlyAmericancities,particularlythoseintheNortheast,haddevelopedatatremendouspace,leavingsomelongingforareturntosimplerlifestyles.Theywerecrowded,employmentwasoftenlimitedtothefactories,andsmokefromcoal-burningindustrialfacilitiespollutedtheair.FormanyAmericans,theurbanlandscapedidnotmatchtheirimage'oftheideallife.3.Yeteconomicpressurewaslikelytheprimarycatalystforwestwardmigration.Forsomefamiliesintheearly1800s,itwasdifficulttoobtainenoughresourcestoliveon.ThiswastrueintheSouthaswellastheNorth,whereinsteadoffactoriestheexpansiveplantationsruledtheeconomy.Aprivilegedfewownedmostofthefarmlandanddominatedtheagriculturalmarketsothatsmallfarmershadtroublemakingmoney.Americansstrugglingundersuchconditionswereveryreceptivetothereportsconstantlyarrivingfromwesternsettlers,whichdescribedvastregionsofbountifulfarmlandwaitingtobeclaimed.Theseaccountswereoftenterriblymisleading,emphasizingthepositiveaspectsofmigrationwhileignoringthenegative,buttheynonethelessconvincedmanythattheirfortuneslayonthewesternfrontier.4.TheU.S.governmentdideverythingitcouldtoencouragethemigrationtrend,seeingitasthebestmethodforensuringthatAmerica,ratherthantheMexico,England,ortheNativeAmericans,gainedcontrolofthewesternterritories,Politicianspassedaseriesofmeasuresthatmadelandavailabletofarmers--orhomesteaders--atdrasticallyreducedratesor,inmanycases,forfree.Forexample,soldierswhoservedintheWarof1812againstBritainwerepromisedtractsofwesternfarmland,andsixmillionacresweredistributedunderthisarrangement.Congress'sPreemptionActof1841gavesquatters,peoplewhohadbegunlivingonapieceoflandwithoutownershipofit,theopportunitytopurchaseupto160acresforjust$1.25peracre.Thisconceptwasexpandedunderthe1862HomesteadAct,whichallowedanycitizentoclaima160-acreplotfornothingmorethanthetrivial$10feechargedtofileanapplication.Then,ifthatpersonestablishedafarmonthelandandimproveditforfiveyears,heorshewouldbegrantedownershipofit.5.Whilethesegovernmentpoliciesspurredmigration,theadventofnewtransportationtechnologiesultimatelyenabledthelarge-scalesettlementofwesternregions.Intheearly1800scommunitieshadtoremainclosetomajorrivers,fortheseprovidedtheonlysuremeansoftransportinggoodsbacktotheeasternmarkets.Overlandtransportationbyhorse-drawnwagonwassimplytooslowandcostly.Constructionofcanalswasthefirstattempttoaddressthisproblem.TheErieCanal,running363milesfromLakeErietotheHudsonRiveratAlbany,resultedinasignificantdropinthecostofshippingmerchandisefromBuffalotoNewYorkCity,from19to2centsaton.Inaddition,theintroductionofthesteamboatinthefirsthalfofthecenturyledtogreaterutilizationofwaterroutessuchastheMississippiandMissouriRivers.Thebiggestchangeoccurredin1869whenoverlandtransportbecamefeasible.Thetranscontinentalrailroadwascompletedthatyear,solidifyingthecountry'sclaimtoalllandinbetweenthecoasts,andproducingthemostimportantchangesforwesternsettlers,Westernpioneerswerenolongerisolated,andtheirtownshipsquicklygrewtobecomesomeofAmerica'smostimportantcities.

SOIL QUALITY1 Soil is a renewable resource, but only on a very long time scale, as it takes hundreds or thousands of years for the natural processes of erosion, organic decay, and accumulation to create soils．Soil quality and the potential to produce crops can vary enormously from region to region and among various soil types． 2 One important factor affecting the productivity of soils ever time is agriculture．Top-quality lands are brought into production earlier because of their higher potential to produce food．As more and more land has been brought under agricultural production, the average quality of land has decreased, reducing potential productivity per hectare．Crops deplete soil fertility by consuming nutrients, and this eventually reduces crop yields．Poor management practices lead to soil compaction and soil pollution as well as loss of soil cover．Without proper management and the constant addition of nutrients and energy in the form of fertilizers and irrigation, crop production falls over time． 3 Within the scientific community, there is little doubt that soil quality is diminishing in many areas around the world．Scientists have found that the quality of one quarter of the world's soils has experienced some degradation, and the pace of degradation has accelerated over the past 50 years．The loss of soil fertility has caused a slowing in the growth of agricultural productivity．Annual crops tend to degrade soils more than perennial crops, and common property lands generally suffer more degradation than private lands． 4 Today, irrigated cropland produces about one-third of the world's food．Approximately 18 percent of the world's cropland is irrigated, and scientists project this amount to double by 2020．Irrigation can increase crop yields per hectare to two or three times the yields of land watered only by rain．However, there are also some harmful side effects．Besides increasing crop productivity in the short run, irrigation can lead to sharp drops in crop productivity in the long run by causing excessive salt buildup and rising water tables． 5 One of the most critical soil quality problems related to irrigation is the increase in concentration of dissolved salts．This process, salinization, affects an estimated one-fourth of the world's irrigated cropland．In some places, irrigation water contains as much as 3.5 tons of salt per 1.000 cubic meters．As the water flows over and through the ground, it dissolves salts, increasing the salinity of the water．Since some crops require 6.000 to 10.000 cubic meters of water per hectare, land can receive tens of tons of salt per hectare． As the water evaporates, high concentrations of salts such as sodium chloride are left behind in the topsoil．Salt buildup can stunt crop growth, decrease yields, kill crop plants, and eventually make the land unproductive． 6 A problem that often accompanies salinization in dry regions is waterlogging, which often occurs when farmers apply heavy amounts of irrigation water in an attempt to prevent salts from accumulating．However, unless the water drains properly, it collects underground and gradually raises the water table closer to the surface, thereby bringing salts to the surface and concentrating them．Saltwater then envelops the fragile root systems of plants, killing the plants and converting fertile fields to wet deserts．This is a particularly serious problem in California's heavily irrigated San Joaquin Valley, where soils contain a clay layer that prevents water from flowing through the ground．Worldwide, at least one-tenth of all irrigated land is subject to waterlogging． 7 Another serious soil problem is erosion, the loss of soils from water and wind action． Soil erosion occurs on agricultural land without vegetative cover for protection or because of poor agricultural management．Scientists estimate that topsoil on cultivated land is being lost 16 to 300 times faster than it is being replaced．In many parts of the world, a shift away from traditional agricultural practices is placing greater pressure on the soil, which in turn is causing an increase in soil erosion rates．Studies in the United States suggest that the loss of just 2.5 centimeters of topsoil reduces corn and wheat yields by 6 percent．Glossary: degradation: loss of quality

AirBagAnairbagisaninflatablecushiondesignedtoprotectautomobileoccupantsfromseriousinjuryinthecaseofacollision.Theairbagispartofaninflatablerestraintsystem,alsoknownasanaircushionrestraintsystem(ACRS)oranairbagsupplementalrestraintsystem(SRS),becausetheairbagisdesignedtosupplementtheprotectionofferedbyseatbelts.Seatbeltsarestillneededtoholdtheoccupantsecurelyinplace,especiallyinsideimpacts,rearimpacts,androllovers.Upondetectingacollision,airbagsinflateinstantlytocushiontheexposedoccupantwithabiggas-filledpillow.Atypicalairbagsystemconsistsofanairbagmodule,crashsensors,adiagnosticmonitoringunit,asteeringwheelconnectingcoil,andanindicatorlamp.Thesecomponentsareallinterconnectedbyawiringharnessandpoweredbythevehicle'sbattery.Airbagsystemsholdareservechargeaftertheignitionhasbeenturnedofforafterthebatteryhasbeendisconnected.Sincecomponentsvitaltothesystem'soperationmightsitdormantforyears,theairbagcircuitryperformsaninternal"self-test"duringeachstartup,usuallyindicatedbyalightontheinstrumentpanelthatglowsbrieflyateachstartup.Theairbagtracesitsorigintoair-filledbladdersoutlinedasearlyas1941andfirstpatentedinthe1950s.Earlyairbagsystemswerelargeandbulky,primarilyusingtanksofcompressedorheatedair,compressednitrogengas(N2),freon,orcarbondioxide(CO2).Someoftheearlysystemscreatedhazardousbyproducts.Oneparticularsystemusedgunpowdertoheatupfreongas,producingphosgenegas(COCl2)--anextremelypoisonousgas.OneofthefirstpatentsforautomobileairbagswasawardedtoindustrialengineerJohnHetrickonAugust18,1953.ConceivedbyHetrickafteranearaccidentin1952,thedesigncalledforatankofcompressedairunderthehoodandinflatablebagsonthesteeringwheel,inthemiddleofthedashboard,andintheglovecompartmenttoprotectfrontseatoccupants,andonthebackofthefrontseattoprotectrearseatpassengers.Theforceofacollisionwouldpropelaslidingweightforwardtosendairintothebags.Manyotherinventorsandresearchersfollowedsuit,allexploringslightlydifferentdesigns,sothattheexacttechnicaltrailfromtheearlydesignstothepresentsystemisimpossibletonotewithcertainty.In1968,JohnPiet,achemistforTalleyDefenseSystems,pioneeredasolidpropellantusingsodiumazide(NaN3)andametallicoxide.Thiswasthefirstnitrogen-generatingsolidpropellant,anditsoonreplacedtheolder,bulkiersystems.Sodiumazideinitssolidstateistoxicifingestedinlargedoses,butinautomotiveapplicationsiscarefullysealedinsideasteeloraluminumcontainerwithintheairbagsystem.Sincethe1960s,airbag-equippedcarsincontrolledtestsandeverydayusehavedemonstratedeffectivenessandreliability.TheInsuranceInstituteforHighwaySafetyconductedastudyofthefederalgovernment'sFatalAccidentReportingSystemusingdatafrom1985to1991,andconcludedthatdriverfatalitiesinfrontalcollisionswereloweredby28percentinautomobilesequippedwithairbags.Accordingtoanotherstudyconductedin1989byGeneralMotors,thecombinationoflap/shouldersafetybeltsandairbagsinfrontalcollisionsreduceddriverfatalitiesby46percentandfrontpassengerfatalitiesby43percent.Inresponsetoconsumers'increasedsafetyconcernsandinsuranceindustrypressure,thefederalgovernmenthasforcedautomobilemanufacturerstoupgradetheirsafetyfeatures.First,DepartmentofTransportation(DOT)regulationsrequireallcars,beginningwithmodelyear1990,soldintheUnitedStatestobeequippedwithapassiverestraintsystem.Ifcarmanufacturerschooseanairbag,thenregulationsrequireonlyadriver's-sidesystemuntilmodelyear1994,whenairbag-equippedcarsmustincludepassiveprotectiononthepassenger'ssideaswell.A1991lawrequiresdriverandpassengerairbagsinallcarsbythe1998modelyearandinlighttrucksandvansby1999.Glossary:module:containsaninflatororgasgeneratorandanairbagpassiverestraintsystems:requirenoactivationbytheoccupant--involvetheuseofautomaticseatbeltsand/ortheuseofairbags

Orchid Millions of years ago when dinosaurs inhabited the earth, a beautiful flowering plant called the orchid came into existence. Throughout the span of time some plants have seen their demise through evolution, but the orchid has continued to grow, survive, and thrive in the wild in all areas of the world except Antarctica. Orchids have adapted to a multitude of environments and grow in areas such as steaming jungles and tropical rain forests, meadows, mountainsides, woodlands, barren tundra. They even grow on rocks and some have been reported to grow underground. Today, more than 35,000 species of orchids, divided into around 850 genera, thrive throughout the world. ? People have been intrigued with orchids for centuries. During the times of Confucius, the Chinese people called orchids the "plant of the king"s fragrance" and during the Middle Ages, orchids were used as important ingredients in herbal remedies. Throughout history orchids have been regarded as symbols—of love, beauty, wealth, and virility—and have been used as an aphrodisiac in love potions. Orchids, considered attractive and unusual flowers, have been collected since the early 1700s. [■] Botanists and amateur growers considered orchids a curiosity when these plants were introduced in Britain by sea ship captains who had traveled to faraway lands. In 1818, William Cattley, an English patron of horticulture and a sea ship captain, accidentally introduced the orchid to Britain when he nurtured a bulb-like item he found in packing material surrounding the tropical plants he had imported from Brazil. A gorgeous, large-flowered, lavender orchid which is commonly referred to as a "corsage orchid" and the "queen of flowers" was the result of Cattley"s planting. [■] Collecting orchids became so popular by the late 1800s that many species of orchids were put on an "endangered" list in Britain because collectors had stripped entire forests of the desired plants. [■] Cultivating orchids, which has been done in Europe for almost three hundred years, is still being done today but most species are now being cultivated from seed. [■] Growing orchids may not be easy for everyone but it need not be difficult, either. Most species of orchids will grow under normal household conditions if they receive the proper care. Plants need to be potted correctly. The orchid"s bare roots should be placed in the smallest pot the roots will fit into. Orchids may not need to be repotted for as long as two to three years. Most, but not all orchids, show better growth in clay pots. Bark or potting medium should be packed around the roots tightly. Fir bark, cypress bark, and peat moss serve as good potting mediums. Coconuts also make an excellent potting choice. Potting mixtures should hold moisture, allow the orchid roots to "breathe" by providing adequate air space, and not decompose in a short period of time. Coconuts are considered to be a perfect growing mixture because they are durable, environmentally friendly, extremely absorbent, and hold enormous amounts of air at the same time they hold water. ? Proper lighting is also important in growing orchids. Some plants require indirect light and other require filtered sunlight. Plant leaves should not be warm, and plants with medium green leaves are healthy plants. All orchids need to be fed to help them grow. Fertilizers with balanced or high amounts of phosphorous produce healthy, blooming plants. Most orchids like temperatures of 60 to 70 degrees Fahrenheit and humidity in the range of 50 to 60 percent. Good air circulation is important for plant growth and thorough watering should take place once or twice each week. When, and if, orchids attract pests such as mites or aphids, the plants should be dusted or cleaned. ? Throughout history the orchid has symbolized romance. Chocolatiers decorate luscious, beautiful candies with this amazing flower. Greeting card companies attractively portray the loveliness of orchids on their cards and gift wraps, and florists prepare elegant orchid corsages and wedding bouquets. Orchids, once considered to be symbols of wealth and viewed as exotic, rare plants which were only able to be admired in botanical gardens, are no longer placed in those categories. Today orchids are affordable and offer a modem, contemporary look for weddings and home decorating. Orchid growers have obtained permission from several administrations to honor Bess Truman, Pat Nixon, Mamie Eisenhower, Nancy Reagan, and Hillary Rodham Clinton, former First Ladies, by naming orchids after them. The tiny, unknown bulb taken to England in plant packing material in error in 1818 has presented to the world a special, stylish, and prized flower the world can appreciate. Glossary genera: the usual major subdivision of a family or subfamily in the classification of organisms aphrodisiac: arousing sexual desire bark: the external covering of the woody stems, branches, and roots of plants aphid: any of numerous tiny soft-bodied insects of the family Aphididae of worldwide distribution

"TheHydrologicCycle"→Thehydrologiccycleisthetransferofwaterfromtheoceanstotheatmospheretothelandandbacktotheoceans.Theprocessesinvolvedincludeevaporationofwaterfromtheoceans;precipitationonland;evaporationfromland;andrunofffromstreams,rivers,andsubsurfacegroundwater.Thehydrologiccycleisdrivenbysolarenergy,whichevaporateswaterfromoceans,freshwaterbodies,soils,andvegetation.Ofthetotal1.3billionkmwateronEarth,about97%isinoceans,andabout2%isinglaciersandicecaps.Therestisinfreshwateronlandandintheatmosphere.AlthoughitrepresentsonlyasmallfractionofthewateronEarth,thewateronlandisimportantinmovingchemicals,sculpturinglandscape,weatheringrocks,transportingsediments,andprovidingourwaterresources.Thewaterintheatmosphere-only0.001%ofthetotalonEarth-cyclesquicklytoproducerainandrunoffforourwaterresources.Especiallyimportantfromanenvironmentalperspectiveisthatratesoftransferonlandaresmallrelativetowhat"shappeningintheocean.Forexample,mostofthewaterthatevaporatesfromtheoceanfallsagainasprecipitationintotheocean.Onland,mostofthewaterthatfallsasprecipitationcomesfromevaporationofwaterfromland.Thismeansthatregionalland-usechanges,suchasthebuildingoflargedamsandreservoirs,canchangetheamountofwaterevaporatedintotheatmosphereandchangethelocationandamountofprecipitationonland-waterwedependontoraiseourcropsandsupplywaterforoururbanenvironments.Furthermore,aswepaveoverlargeareasoflandincities,stormwaterrunsoffquickerandingreatervolume,therebyincreasingfloodhazards.Bringingwaterintosemi-aridcitiesbypumpinggroundwaterortransportingwaterfromdistantmountainsthroughaqueductsmayincreaseevaporation,therebyincreasinghumidityandprecipitationinaregion.Approximately60%ofwaterthatfallsbyprecipitationonlandeachyearevaporatestotheatmosphere.Asmallercomponent(about40%)returnstotheoceansurfaceandsubsurfacerunoff.Thissmallannualtransferofwatersuppliesresourcesforriversandurbanandagriculturallands.Unfortunately,distributionofwateronlandisfarfromuniform.Ashumanpopulationincreases,watershortageswillbecomemorefrequentinaridandsemi-aridregions,wherewaterisnaturallynonabundant.→Attheregionalandlocallevel,thefundamentalhydrologicalunitofthelandscapeisthedrainagebasin(alsocalledawatershedorcatchment).Adrainagebasinistheareathatcontributessurfacerunofftoaparticularstreamorriver.Thetermdrainagebasinisusuallyusedinevaluatingthehydrologyofanarea,suchasthestreamfloworrunofffromhillslopes.Drainagebasinsvarygreatlyinsize,fromlessthanahectare(2.5acres)tomillionsofsquarekilometers.Adrainagebasinisusuallynamedforitsmainstreamorriver,suchastheMississippiRiverdrainagebasin.→Themainprocessinthecycleistheglobaltransferofwaterfromtheatmospheretothelandandoceansandbacktotheatmosphere.Together,theoceans,icecapsandglaciersaccountformorethan99%ofthetotalwater,andbotharegenerallyunsuitableforhumanusebecauseofsalinity(seawater)andlocation(icecapsandglaciers).Onlyabout0.001%ofthetotalwateronEarthisintheatmosphereatanyonetime.However,thisrelativelysmallamountofwaterintheglobalwatercycle,withanaverageatmosphericresidencetimeofonlyabout9days,producesallourfreshwaterresourcesthroughtheprocessofprecipitation.→Onaglobalscale,then,totalwaterabundanceisnottheproblem;theproblemiswater"savailabilityintherightplaceattherighttimeintherightform.Watercanbefoundineitherliquid,solid,orgaseousformatanumberoflocationsatornearEarth"ssurface.Dependingonthespecificlocation,theresidencetimemayvaryfromafewdaystomanythousandsofyears.However,asmentioned,morethan99%ofEarth"swaterinitsnaturalstateisunavailableorunsuitableforbeneficialhumanuse.Thus,theamountofwaterforwhichallthepeople,plants,andanimalsonEarthcompeteismuchlessthan1%ofthetotal.Astheworld"spopulationandindustrialproductionofgoodsincrease,theuseofwaterwillalsoaccelerate.Theworldpercapitauseofwaterin1975wasabout185,000gal/yr.Andthetotalhumanuseofwaterwasabout1015gal/yr.Today,worlduseofwaterisabout6,000,whichisasignificantfractionofthenaturallyavailablefreshwater.

ElephantIntelligenceInmanycultures,elephantsaresymbolsofintelligenceandwisdom.Elephantsdisplaymanybehaviorsthatseemtobetheresultofaconsciousintelligence.However,whetherthatintelligenceissimilartoourownisamatterofheateddebate.Somearguethattheevidenceforelephantintelligenceissooverwhelmingthatitcannotbedoubted.Otherssaythattheclaimsofelephantintelligencearebackedupbymostlyanecdotal1evidence,andthattheytellusmoreaboutourdesiretoanthropomorphize2othercreaturesthantheytellusaboutelephantsthemselves.Stillothersarepreparedtoadmitthatelephantsmaypossesssomesortofconceptualabilitythatcouldbedescribedasintelligence,buttheyalsocautionagainstsimplyreadinghumanthoughtpatternsintothemlestwefailtounderstandthetruecomplexityoftheanimal.Whateverviewonesubscribesto,therecanbenodoubtthatproponentsofthetheoryofelephantintelligencehavebuiltastrongcasefortheirposition.Oneofthestandardwaysoftestingforanimalintelligenceinvolvesexaminingtheirreactiontotheirownreflectioninamirror.Mostanimalsareconfusedbytheimage,mistakingitforanothercreature.Infact,onlyveryfewspecies,includingchimpanzeesanddolphins,seemtorecognizetheimageforwhatitis.Invariousexperimentswithcaptiveelephants,scientistshavenotedbehaviorindicatingthatelephantsalsorealizethattheirreflectionisaself-image.Themosttellingclueisthatnoelephanthaseverbeenknowntoengageitsreflectioninthesortofsocialgreetingbehaviorthatnormallyoccurswhentwoelephantsmeet.Inaddition,elephantslookingintomirrorsactinmuchthesamewayhumansdo.Iftheyaredirty,theywillattempttocleanthemselves,usingtheirreflectionasaguide.Iftheyhaveneverseentheirreflectionbefore,theymaymovearoundtotrytoseethemselvesfromdifferentangles,exploringtheirownappearance.Thatelephantscanrecognizetheirreflectionforwhatitisimpressesscientistsbecauseitmeansthatelephantsapparentlyhaveasenseofselfthatislackinginmanyotheranimals.Thissenseofselfisconsideredoneofthefundamentalcharacteristicsofatrulysentientintelligence.Anotherstrikingaspectofelephantbehaviorthatindicatestheypossessahighlevelofintelligenceistheirseemingawarenessofdeath.Mostanimalspossesssharplyhonedinstinctsofself-preservation,buttheydonotactinwaysthatrevealanyspecialsenseofmortality.Atmost,suchanimalsmayengageinbehaviorthatseemstodisplaysadnessatthelossoftheirmateoryoung,butthesedisplaysaresignsoftemporarydistressthatsoonfade.Inthesecases,mostscientistsbelievethattheyareinstinctualstressreactionsratherthanindicatorsofagenuineawarenessofdeath.Elephants,incontrast,reacttodeathinmanyofthesamewaysthathumansdo.■(A)Whenamemberoftheherdperishes,therestoftheherdmembersgatheraroundthecorpse,strokingandtouchingitwiththeirtrunks.■(B)Thisbehaviorisconsistentwithhumanfuneralritesinwhichthedeadbodyisdisplayedatawakesothatfamilyandfriendscanbidthedepartedfarewell.■(C)Moreover,anecdotalevidenceexiststhatelephantswillpausewhentravelingthroughplaceswheretheyknowanotherelephanthasdied,asifreflectingonthedeceased.■(D)Allofthesebehaviorsindicatethatelephantsarecapableofgraspingdeathasanintellectualconcept.Notonlydoelephantsapparentlyconceptualizeatalevelnotseeninanyspeciesotherthanhumans,theyarealsocapableofapplyingtheirknowledgetoachievegoals.Alongwiththehigherprimates,elephantsaretoolusers.Forinstance,elephantswilloftengraspbranchesintheirtrunksandusethestickstoscratchthemselvesinplaceswheretheycouldnototherwisereach.Thisbehavior,andinfactvirtuallyallelephantbehavior,islearnedratherthaninstinctual.Youngelephantshavetobetaughteverything,includinghowtousetheirtrunkstodrink.Withoutthisinstruction,theirattemptstodrinkthroughtheirnosesendinmuchthesamewaytheywouldforanyotheranimal:theychokeandsplutterhelplessly.Thistotalrelianceonlearningisextremelyrareintheanimalkingdomandis,ofcourse,mostnotableinourownspecies.Andinhumans,justastheneedtoprotectandteachouryoungisbelievedtohavegivenrisetoournatureassocialanimals,sotoothesameneedinelephantsisthoughttounderlietheirowncomplexsocialstructures.

{{B}}Narrator{{/B}} Listen to a part of a discussion in a biology class.

Reading5"PhysicalandChemicalPropertiesandChanges"→Sugar,water,andaluminumaredifferentsubstances.Eachsubstancehasspecificpropertiesthatdonotdependonthequantityofthesubstance.Propertiesthatcanbeusedtoidentifyorcharacterizeasubstance—anddistinguishthatsubstancefromothersubstances--arecalledcharacteristicproperties.Theyaresubdividedintotwocategories:physicalpropertiesandchemicalproperties.Thecharacteristicphysicalpropertiesofasubstancearethosethatidentifythesubstancewithoutcausingachangeinthecompositionofthesubstance.Theydonotdependonthequantityofsubstance.Color,odor,density,meltingpoint,boilingpoint,hardness,metalliclusterorshininess,ductility,malleability,andviscosityareallcharacteristicphysicalproperties.Forexampie,aluminumisametalthatisbothductileandmalleable.Anotherexampleofaphysicalpropertyiswater.Whetherasmallpanofwaterisraisedtoitsboilingpointoraverylargekettleofwaterisraisedtoitsboilingpoint,thetem-peratureatwhichthewaterboilsisthesamevalue,100degreesCor212degreesF.Similarly,thefreezingpointofwateris0degreesCor32degreesF.Thesevaluesareindependentofquantity.Characteristicpropertiesthatrelatetochangesinthecompositionofasubstanceortohowitreactswithothersubstancesarecalledchemicalproperties.Thefollowingquestionspertaintothechemicalpropertiesofasubstance.1.Doesitburninair?2.Doesitdecompose(breakupintosmallersubstances)whenheated?3.Whathappenswhenitisplacedinanacid?4.Whatotherchemicalswillitreactwith,andwhatsubstancesareobtainedfromthereaction?Characteristicphysicalandchemicalproperties—alsocalledintensiveproperties—areusedtoidentifyasubstance.Inadditiontothecharacteristicphysicalpropertiesalreadymentioned,someintensivephysicalpropertiesincludethetendencytodissolveinwater,electricalconductivity,anddensity,whichistheratioofmasstovolume.Additionalintensivechemicalpropertiesincludethetendencyofasubstancetoreactwithanothersubstance,totarnish,tocorrode,toexplode,ortoactasapoisonorcarcinogen(cancer-causingagent).Extensivepropertiesofsubstancesarethosethatdependonthequantityofthesample,includingmeasurementsofmass,volume,andlength.Whereasintensive:propertieshelpidentifyorcharacterizeaparticularkindofmatter,extensivepropertiesrelatetotheamountpresent.Ifalumpofcandlewaxiscutorbrokenintosmallerpieces,orifitismelted(achangeofstate),thesampleremainingisstillcandlewax.Whencooled,themoltenwaxreturnstoasolid.Intheseexamples,onlyaphysicalchangehastakenplace;thatis,thecompositionofthesubstancewasnotaffected.→Whenacandleisburned,therearebothphysicalandchemicalchanges.Afterthecandleislighted,thesolidwaxneartheburningwickmelts.Thisisaphysicalchange;thecompositionofthewaxdoesnotchangeasitgoesfromsolidtoliquid.Someofthewaxisdrawnintotheburningwickwhereachemicalchangeoccurs.Here,waxinthecandleflamereactschemicallywithoxygenintheairtoformcarbondioxidegasandwatervapor.Inanychemicalchange,oneormoresubstancesareusedupwhileoneormorenewsubstancesareformed.Thenewsubstancesproducedhavetheirownuniquephysicalandchemicalproperties.Theapparentdisappearanceofsomething,likethecandlewax,however,isnotnecessarilyasignthatweareobservingachemicalchange.Forexample,whenwaterevaporatesfromaglassanddisappears,ithaschangedfromaliquidtoagas(calledwatervapor),butinbothformsitiswater.Thisisaphasechange(liquidtogas),whichisaphysicalchange.Whenattemptingtodeterminewhetherachangeisphysicalorchemical,oneshouldasktheCriticalquestion:Hasthefundamentalcompositionofthesubstancechanged?Inachemicalchange(areaction),ithas,butinaphysicalchange,ithasnot.Glossaryductility:canbedrawnintowiremalleability:canbeshapedviscosity:thick,resistanttoflow

THE FIVE-SEVEN SHIFT 1 All major theories of child psychology state that children undergo a major change between the ages of five and seven. In classical learning theory, this is a time when the simplest forms of learning give way to learning that involves more complex mental processes. According to psychologist Jean Piaget, the period from five to seven years old is a transition to operational thought, when children are able to move beyond using only their senses toward using a new set of rational-thinking skills. Because several cognitive changes occur in children between ages five and seven, this period is called the five-seven shift. The shift is biological in nature and involves fundamental growth in the brain and stabilization of brain-wave rhythms into a basically adult pattern. The five-seven shift involves many physical changes, such as the loss of the "baby teeth" and an increase in the rates of height acquired and weight gained. 2 By the time they are five years old, children can understand and use symbols. They have developed the ability to use words, gestures, and pictures to stand for "real life" objects, and they are skilled in deploying various symbol systems, such as language or drawing. However, a five-year-old child is able to focus attention on only one quality of an object at a time, such as the object"s size or shape. The use of symbolization continues to evolve, reaching a peak around the age of seven or eight, when children become capable of concrete operations. When this happens, they can solve problems by using rational thought to make generalizations from their own experience. 3 By the age of seven or eight, a new set of abilities allows children to reason systematically about the world of objects, quantity, time, space, and causality. According to Piaget, this is because an "extra card" is added to the child"s mental "computer" during the five-seven shift. The development of operational thought enables the child to appreciate the relations among a series of actions upon objects. For example, the child understands that a scene can be viewed from a different perspective and still contain the same elements. The child also understands that objects can be rearranged and still have the same quantity and that a substance can be changed in shape without its mass or volume being affected. 4 Piaget discovered the most widely known hallmark of the five-seven shift, an understanding of conservation, the idea that some properties stay the same despite changes in appearance. In one of Piaget"s classic experiments on the conservation of quantity, the experimenter shows children of different ages two straight rows of coins, each with six coins pressed close together, beside each other on a table. The experimenter asks each child subject whether both rows have the same number of coins or whether one row has more. Then the experimenter spreads out the coins of one row to make the line look longer. The child must now say whether one row has more coins. Children younger than five years old cannot understand conservation, so they invariably say that the spread-out row has more coins than the other row. 5 Like most age-related tasks for children, there are other ways to set up the task. In a similar experiment, water is poured into two identical glasses until the child subject agrees that each contains an equal amount. Then the experimenter pours water from one of these glasses into a tall, thin glass. At that point, the child is asked whether one glass has more water than the other. Five-year-old children will say that there is more water in the tall, thin glass. When asked why they think that, many will confidently say, "Because it"s taller." Older children, however, are likely to reply, "It looks like there"s more water in this one because it"s taller, but they"re really the same." Such experiments show a difference between children of five years and children of eight years. The older children can solve the task promptly, easily, under a wide variety of conditions, and without being taught. The younger children, even if they are taught about conservation, cannot do what the five-seven shift will do for them naturally: provide them with a more developed brain. Glossary: cognitive: relating to mental processes

ContinentalDriftContinentaldrift,andthesubsequenttheoryofplatetectonics,formsthemodernframeworkforgeologicalstudyoftheEarth.Continentaldriftstemsfromscientificnotionsasearlyasthe16thcenturythattheEarth'scontinentswereonceasinglelandmass,whichscientistshavetermedPangaea,meaning"alllands"inGreek.In1912,GermanmeteorologistAlfredWegenerproposedthatnaturalforcessuchasearthquakesandfloodsbrokePangaeaapartbetween225and200millionyearsago,anditeventuallyfragmentedintothecontinentsasweknowthemtoday.Wegenerbasedhistheoryonfourmajorobservations:first,theamazingfitoftheAfricanandSouthAmericancontinents;second,thesimilaritiesofunusuallystructuredplantandanimalfossilsdiscoveredalongthecoastlinesofSouthAmericaandAfrica,eventhoughtheyareseparatedbytheAtlanticOcean;third,similaritiesinrocksandicesheetsonthesetwocontinents;andfourth,evidencethatsomeancientclimateswerediametricallyoppositeofmodernones.Wegener'stheoryofcontinentaldriftwouldeventuallysparkanewwayofviewingtheEarth.Initially,however,colleaguesgenerallydismisseditasabsurd,despitethefactthatitseemedtocomplementavailablescientificinformation.TheirprimarycriticismwasWegener'sinabilitytoadequatelyexplainhowthelargemassesoflandcoulddriftsuchgreatdistances.■(A)Wegenerspeculatedthattheysimplyplowedthroughtheoceanfloor,butEnglishgeophysicistHaroldJeffreysrefutedthatcontention,notingthatitisphysicallyimpossibleforagargantuanmassofsolidrocktodosowithoutbreakingup.■(B)Itwasnotuntilthe1950s--twodecadesafterWegener'sdeath--thattechnologicaladvancesenabledscientiststoconfirmWegener'shypotheses.Improvedtechniquesinoceanfloormappingrevealedthatthebottomoftheoceanwasnotmostlyflatandfeaturelessasmostscientistshadspeculated,andthatgeologicprocessesonland,suchasearthquakesandvolcaniceruptions,werelinkedtodynamicsontheoceanfloor.■(C)ScientistsdiscoveredthathotrockboilsupfromtheEarth'smantle1nearridgesinthemiddleoftheocean,spreadingovertheseafloorandformingnewoceaniccrust.■(D)Asthiscrustspreads,itmovescontinentsanaverageofoneortwocentimeterseachyear.Scientistsalsofoundthatasnewcrustformsatoceanridges,oldercrustdescendsintotrenches2attherimofthePacificOceanBasin,effectivelyrecyclingtheoceanbasinsandmaintainingtheEarthatasteadysize.Seismicactivityismostprominentinearthquakezonesparalleltothesetrenchesattheedgeofcontinents,likelyduetothefactthatsinkingcrustmelts,causinghotrocktobubbleup,leadingtoeruptionsandviolentquaking.Thesefindingsontheoceanfloorledtothetheoryofplatetectonics,whichholdsthattheEarth'soutermostlayerconsistsofmorethanadozenlargeandsmallplates--massiveslabsofsolidrock,bothaboveandbeneaththewater--thataredriftingaboutthesurfaceoftheEarth,occasionallycolliding,rubbingagainsteachother,clusteringandseparating,andevendisappearingcompletelyunderoneanother.Theseinteractionsareconstantlyshapingthefaceoftheplanet,signifiedbytheterm"tectonics"fromtheGreekwordmeaning"tobuild."Theresultsofplate-tectonicforcesaremostevidentatplateboundaries--narrowzonesbetweenplates.Atdivergentboundaries,platespullawayfromeachother,creatingnewcrust.AprominentexamplecanbeseeninIceland,whichissplittingastheNorthAmericanPlatemoveswestwardrelativetotheEurasianPlate.Atconvergentboundaries,crustisdestroyedasoneplatedivesunderanother.Thistendstoformmountainrangesoncontinental,orsurface,plates,suchastheSouthAmericanAndesandtheAsianHimalayas.Attransformboundaries,platesslidehorizontallypasteachotherandcrustisneithercreatednordestroyed.Sincetheplateslacksmoothedges,pressureisgenerallybuiltupandsuddenlyreleased,makingthesetypesofboundaries--suchastheSanAndreasFaultinCalifornia--particularlysusceptibletoearthquakes.Atafourthtypeofboundary,calledplateboundaryzones,therearebroadareaswhereboundariesareill-definedandtheeffectsofplateinteractionarenotwellunderstood.Becauseplateboundaryzonesfeatureatleasttwolargeplatesandonesmallplatecaughtbetweenthem,theyhavecomplicatedgeologicalstructuresandearthquakepatterns.Thetheoryofplatetectonicshasgainedwidespreadscientificacceptance,thoughtherestillremainsdebateoverspecificaspects.Oneofthese,ironically,isthesamequestionthatdoggedWegener:Whatisthenatureoftheforcespropellingtheplates?

THE PHOTOGRAPHS OF JACOB RIIS 1 In the late nineteenth century, New York"s Lower East Side had the highest concentration of people in the world. Over one million residents lived in extreme poverty, with 300,000 of them packed into one square mile alone. Most were immigrants from Europe and Asia. Men, women, children, and the elderly all worked for low wages in the thousands of sweatshops that made clothing, cigars, furniture, and tinware. Few of the realist painters of the time wanted to paint this New York; it was a photographer and writer, Jacob Riis, who opened the subject to a wide public. 2 Jacob Riis was born in Denmark and immigrated to the United States in 1870, at the age of twenty-one. He landed in New York and got a job as a police court reporter for the New York Tribune. The police headquarters was located in the heart of the East Side slum district, and Riis came to know thousands of the local poor. What he saw inspired him to fight for the elimination of slums using the tools of journalism. At that time, American journalism was changing. The urban population was multiplying rapidly, and there was an explosion of newspapers. The papers aimed to reach larger audiences, which led them to increase the number of human-interest stories—stories not just about the comfortable classes, but about the "other half" and how it lived. 3 Jacob Riis became New York"s chief reporter of urban blight, making a name for himself with his detailed accounts of life in the Lower East Side. Today he is best known as a photographer. In the 1880s, photography was still at an early stage, and news photos were rare. As a good journalist, Riis was quick to see that recent developments in flashlight photography would enable him to dramatize his stories. Photography would be his means for drawing attention to the living conditions of the poor, particularly the immigrant population. He committed himself to this cause, knowing that the affluent and educated half of society could not ignore photographs of how the other half lived. 4 In 1890 he published his photographs in a book, How the Other Half Lives, his most famous work. The book was a bestseller and ran through several editions. The photographs exposed the appalling conditions of the time and were direct evidence of human misery in the immigrant enclaves, back alleys, and cheap lodging houses. Shocked readers saw images of ragged children playing in the street and old people toiling in dim sweatshops. They were horrified by the miserable existence of a million people, the powerless and destitute of America"s "other half." 5 Riis was a member of the new generation of "muckraking" journalists that investigated corruption, injustice, exploitation, and poverty. Like the other muckrakers, Riis made it his mission to seek out and expose the darker side of society. By today"s standards of journalistic etiquette, he was very intrusive, feeling no need to get permission from his subjects before photographing them. Riis and his assistants would burst into tenements and saloons, startling people with their cameras and flashlights. Many of the photographs were taken at night, requiring artificial lighting, which at the time consisted of flash cartridges fired from a revolver into a frying pan. The explosive noise caused terror and confusion. On two occasions, Riis accidentally set fire to rooms he was photographing when the flash cartridge exploded in flames. 6 Still, as a journalist and photographer, Jacob Riis had more of an influence on reforming living conditions than did any of the more conventional social workers of his day. One day Riis received a note that read, "I have read your book and I have come to help." The note was from the head of the New York Police Board of Commissioners, Theodore Roosevelt, who later went on to become president of the United States. Moved by the photographs Riis had taken, Roosevelt instituted a number of social reforms. The photographs in How the Other Half Lives are still prized for their historic value and stand out as proof of the power of pictures to bring about social change.