Beforegoingoutsideinthemorningmanyofuscheckawindowthermometer(温度计)forthetemperature．Thishelpsusdecidewhattowear．1．Wewantourfoodtobeacertaincoldnessintherefrigerator．Wewantitacertainhotnessintheoven．Ifwedon’tfeelwellweuseathermometertoseeifwehaveafever．Wekeepourroomsacertainwarmthinthewinterandacertaincoolnessinthesummer．
Notallthethermometersusethesamesystemtomeasuretemperature．WeuseasystemcalledtheFahrenheitscale．ButmostothercountriesusetheCentigradescale．
Bothsystemsusethefreezingandboilingpointsofwaterastheirguide．2．
Themostcommonkindofthermometerismadewithmercury(水银)insideaclearglasstube．Asmercury(oranyotherliquid)becomeshotitexpands．Asitgetscolderitcontracts(收缩)．Thatiswhyonhotdaysthemercurylineishighintheglasstube．3．
First．Takeaclearglassjuicebottlethathasacap;fillthebottlewithcolouredwater．Tapaholeinthecenterofthecapusingahammerandthicknail．Putthecaponthejar．Thenstickaplasticstraw(吸管)throughthenailhole．4．
Finally．Placeawhitecardontheoutsideofthebottleandbehindthestraw．Nowyoucanseethewaterlevereasily．5．
Asthetemperaturegoesdownthewaterwillcontractandtheleverinthestrawwillcomedown．Perhapsyouwillwanttokeeparecordofthewaterleverinthestraweachmorningforaweek．
A．Peopleusethermometerswhicharemadebythemselveswhentravellingaroundtheworld．
B．Weuseanddependonthermometerstomeasurethetemperatureofmanyotherthingsinourdailylives．
C．Thermometersmeasuretemperaturebyusingmaterialsthatchangeinthesamewaywhentheyareheatedorcooled．
D．Nowthatyouknowthisruleyoucanmakeathermometerofyourownthatwillwork．
E．Thewaterwillriseinthestraw．Asthetemperatureoftheairgoesupthewaterwillexpandandriseevenhigher．
F．Theylabeltheseindifferentways．OntheFahrenheitscalewaterfreezesat32degreesandboilsat212degrees．OntheCelsiusscalewaterfreezesat0degreesandboilsat100degrees．
G．Takewax(youmayuseanoldcandleifyouhaveone)andmeltsomeofitrightwherethestrawisstruckintothecaptoseal(把…粘住)themtogeth
