(精品)Warmingup、Pre-reading、Reading、Comprehending.ppt

Unit 2 Sailing oceansUnit 2 Sailing oceansLead in1.Talk about the four pictures in pre-readingCompass(Sinan)A compass consists of a small magnet balanced on a point so that it can move round in a circle.The magnet is generally called a needle because it is shaped like a needle.One end of the needle is often marked“N”for north,or coloured in some way to indicate that it points toward north.astrolabeastrolabeThe astrolabe measures the height and position of the sun.If you can measure this accurately,a sailor can tell how many degrees the boat is from the North Pole.From this he can tell where the boat is in the ocean.sextantThe sextantThe sextant is a navigational instrument for measuring the angle between the horizon and some object in the sky.First a sailor looks at the horizon through an eyepiece.At the same time he can see light from the sun or a star reflected off a small mirror on top of the instrument,onto a second mirror and into the eyepiece.nautical chartnautical chartNautical Nautical chartschartsn.n.海图海图海图海图,图表图表图表图表vt.vt.制图制图制图制图areare maps of maps of the depth of the seathe depth of the sea and and the the currents of the oceanscurrents of the oceans.TheyThey provide modern sailors with provide modern sailors with routesroutes through the seas,rather like roads through through the seas,rather like roads through the countryside.The information began to the countryside.The information began to be collected in the be collected in the 19th19th century and has century and has continued to continued to be updatedbe updated ever since.These ever since.These charts were not available to Captain Bligh charts were not available to Captain Bligh or or ZhengZheng He.He.Active 1 Fast-readingRead the text quickly and try to get the general idea.It mainly talks about how seamen explored the oceans and what kind of navigational instruments were used at sea before the 17th century.naturenavigationalinstrumentscelestial bodieswildlife the weatherthe sea finding longitude finding latitudenorth star seaweed fog time the bearing circlesuncloudsbirdswindsspeedcompasscomplicatedmathematicaltablesthe astrolabethequadrantthe sextantStructure of the text1.the North Star;the sun2.fresh seaweed;birds;fog;clouds;3.sea currents or tides;winds4.knots;compass;mathematical tablets 5.bearing circle6.astrolabe7.quadrant8.sextantA.to increase the ships speedB.to find longitudeC.to find a land nearbyD.to compare the suns shadow with the position of the sun at middayE.to compare the position of the ship in relation to the sun or starsF.to measure how high stars are above the horizonG.to find a ships positionH.to measure the angle between 2 fixed points outside the ship Active 3 Read this part again and decide the following sentences to be true(T)or false(F).()1.Because they had no modern instruments,seamen had to be at the mercy of the sea.()2.It was considered to be the most useful and least dangerous form of exploration to keep alongside the coastline.()3.Early sailors could use the height of the sun to work out their longitude.()4.In the evening,seaman could follow nesting birds to land even though they were offshore and in the open sea.()5.Winds could accelerate sailing speed and it was always safe and easy to use.FFTFTComprehending1.Read the passage and answer the following questions.1)What is the use of a bearing circle,astrolabe,quadrant or sextant?()What is the use of a compass?()A.To set the course of the ship B.To measure the position of the ship C.To measure the speed of the ship D.To tell the timeAB2)Why are speed and time important in 2)Why are speed and time important in working out the longitude of a ship?working out the longitude of a ship?Speed and time are important in finding Speed and time are important in finding out the longitude of a ship because the out the longitude of a ship because the earth moves fifteen degrees westwards earth moves fifteen degrees westwards every hour.If you know your direction,every hour.If you know your direction,speed and time,you can work out the speed and time,you can work out the approximate longitude or change in your approximate longitude or change in your position in relation to the stars.position in relation to the stars.3)Why is the position of the sun and various 3)Why is the position of the sun and various stars useful for working out latitude?stars useful for working out latitude?The position of the sun and stars are The position of the sun and stars are useful for working out latitude because useful for working out latitude because they are fixed points in the sky and their they are fixed points in the sky and their movements in relation to the earth are movements in relation to the earth are already known.So they can be used to already known.So they can be used to measure a ships position.measure a ships position.2.2.Suppose you were a sea Suppose you were a sea captain aiming to sail captain aiming to sail round Africa.Discuss in round Africa.Discuss in groups:groups:1.What skills would you seek in your sailors?The sailors would need to be excellent navigators,able to cope with both hot and cold weather,experienced in sailing through very bad weather and able to co-operate in a team.2.What problems would you anticipate for this journey?I would anticipate very hot weather(around the equator),cold weather(around Cape of Good Hope),very stormy seas(around the Cape),and problems with food and water,etc.3.3.What would you do if you came What would you do if you came across the following problems across the following problems during your voyage?Read the during your voyage?Read the chart below and fill in your plans of chart below and fill in your plans of action to deal with them.action to deal with them.What would you do if:Plan of actionYou were far from land and a storm arose.Wait till the storm is over,and then find your new position and return to your original course.What would you do if:Plan of actionYou knew your latitude but didnt know your longitude.Use knots to find your speed and work out your approximate longitude.What would you do if:Plan of actionYou were blown offcourse.Use the compass and the astrolabe,quadrant or sextant to find out your position,return to your former course.What would you do if:Plan of actionYou were offshore but you needed more food and water.Follow nesting birds to shore;look for special cloud formations or fog over streams to find land.What would you do if:Plan of actionYou wanted to keep a straight course.Use a compass.What would you do if:Plan of actionYou were lost with no land in sight.Measure your position using the sun or stars;look for sea birds,cloud formations,fog or seaweed to show that land is nearby.4.Read the passage again and use the information to analyse the navigational skills.Using nature1.To find the ships position at sea a sailor 1.To find the ships position at sea a sailor used used the North Star and the sun.the North Star and the sun.2.A sailor knew that land was nearby if he 2.A sailor knew that land was nearby if he saw _saw _ _._.3.Sailors used 3.Sailors used _ _to increase their speed._to increase their speed.fresh seaweed,nesting birds returning fresh seaweed,nesting birds returning home in the evening or foghome in the evening or fog sea currents or tides and sea currents or tides and windswinds4.There were two methods to find longitude:4.There were two methods to find longitude:1)_ 1)_ 2)_ 2)_ Using instrumentsmeasuring time and speedmeasuring time and speedcompass and complicated mathematical compass and complicated mathematical tablestables5 Write down the working principles of the 5 Write down the working principles of the following instruments:following instruments:Bearing circle:Bearing circle:Astrolabe:Astrolabe:to compare the height to compare the height of the sun now with the of the sun now with the position of the sun at position of the sun at midday.midday.to compare the position to compare the position of the ship in relation to of the ship in relation to some stars or the sun some stars or the sun Quadrant:Quadrant:a more precise form of the astrolabe,a more precise form of the astrolabe,to measure how high stars are above the to measure how high stars are above the horizon,and compare that measurement horizon,and compare that measurement with previous measurements(using the with previous measurements(using the ship as one of the fixed points to find its ship as one of the fixed points to find its position)position)Sextant:an updated version of the an updated version of the quadrant and so it was more quadrant and so it was more accurate,to measure the accurate,to measure the angle between two fixed angle between two fixed points outside the ship(using points outside the ship(using two mirrors to find the ships two mirrors to find the ships position).position).5.Imagine you are on a boat with 5.Imagine you are on a boat with twentynine other people.You have a twentynine other people.You have a small box for your personal things small box for your personal things but it can only hole ten items.What but it can only hole ten items.What would you need for a weeks journey would you need for a weeks journey across the North Sea to England?across the North Sea to England?category itemscategoryItemsClothesshoesHygieneToolsbeddingMedicinesshirt,trouserssoapblanketwaterproof bootsknife,scissorssea-sick tablets,Discuss your list with your partner Discuss your list with your partner and combine the two sets of choices and combine the two sets of choices to make a third and better list.Be to make a third and better list.Be prepared to justify your choices to prepared to justify your choices to the class.the class.Homework 1.Review this passage.2.Preview Learning about language.