GPS(globalpositioningsystem)ZhengHe1371-1433HeledalargefleettoexploreSoutheastAsia,IndiaandtheMiddleEastintheMingDynasty.Altogetherhemade7voyagesinthe15thcentury.MarcoPolo1254--1324HeisthemostfamouswesternertotraveltheSilkRoad.Whileinprison,hetoldthestoryofhistravelstoafellowprisonerwhowrotehisadventuresdown.WhenthebookthetravelsofMarcoPolowaspublished,itbecameabest-seller.Scanthewholetextandmakeamind-map.Mind-mapMainideaHowseamenexploredtheoceansbefore17CnaturecoastlinecelestialbodiesNorthStarSunwildlifeseaweedbirdsweatherseacloudsfogwindsnavigationalinstrumentslongitudelatitudetheBearingCircletheAstrolabetheQuadranttheSextantknottedropecompass&mathsComprehendyourgeographicalknowledgeanddiscussthemethodsyouarefamiliarwithandsharewithothers.(Makeadiagramifnecessary)Students’workWorkinpairstodealwiththesituations.Assumethatyouarelostintheseaintheday,howcanyoutelldirections?Assumethatyouarelostintheseaatnight,howcanyoutelldirections?