标出船只的位置.ppt

《标出船只的位置.ppt》由会员上传分享，免费在线阅读，更多相关内容在行业资料-天天文库。

1、SailingtheoceansUnit2Nowadayshowdothesailorsknowthedirectionofnavigationinthesea?JamesCook(1728-1779)MarcoPolo1254-1324ZhengHe1371-1433Howdoyouthinkseamenfoundtheirwaybeforemodernaccuratemethodsofnavigationwereinvented?compassastrolabesextantNauticalchartsThecomp

2、assisusedtohelpfindthedirectionthattheshipneedstogo.Theastrolabemeasurestheheightandpositionofthesun.Thesextantisanavigationalinstrumentformeasuringtheanglebetweenthehorizonandsomeobjectinthesky.Nauticalchartsaremapsofthedepthoftheseaandthecurrentsoftheoceans.The

3、yprovidesailorswithroutesthroughtheseas.Whatdidancientsailorsusetohelpthemselvesnavigateonearth?ReadingUsenaturetohelpUsenavigationalinstrumentstohelpReadthepassageandusetheinformationtoanalysethenavigationalskills.Writetheanswersinyourownwords.ReadingUsingnature

4、1.Tofindtheship’spositionatsea,asailorused_____________________.2.Asailorknewthatlandwasnearbyifhesaw____________________________________________.3.Sailorsused________________________________toincreasetheirspeed.theNorthStarandthesunfreshseaweed,nestingbirdsretur

5、ninghomeintheeveningorfogseacurrentsortidesandwindsReadingUsinginstruments4.Thereweretwomethodstofindlongitude:①_________________________②_______________________.5.Whatistheuseofabearingcircle,astrolabe,quadrantorsextant?()Whatistheuseofacompass?()Atosetthecourse

6、oftheshipBtomeasurethepositionoftheshipCtomeasurethespeedoftheshipDtotellthetimemeasuringtimeandspeedUsingcompassandcomplicatedmathematicaltablesBAReading5.Thereadingpassagemainlywantstotellus_______.A.thatkeepingalongsidethecoastlineisfirstthemostusefulformofexp

7、loration.B.abouttheskillsandnavigationalaidsearlyseamenusedwhilesailingtheoceans.C.thatfindinglongitudeandlatitudeisamusttoplotaship’spositiononamap.D.thatthereisusefulinformationinanencyclopedia.BReadingThesailorswouldneedtobeexcellentnavigators,abletocopewithbo

8、thhotandcoldweather,experiencedinsailingthroughverybadweatherandabletocooperateinateam.Whatskillswouldyouseekinyoursailors?DiscussionLanguagepoints标出船只的位置受---的