人教高中英语选修9 U2 Warming up、Pre-reading、Reading、Comprehending 课件 (共23张PPT).ppt

1、Unit 2 Sailing the oceansTeaching aims1.Let students have some knowledge of early navigation methods.2.train the students reading ability.3.Inspire students to explore more about ancient travelling after class.Zheng HeChristopher ColumbusFerdinand MagellanDo you know them?we call them sailors or nav

2、igatorsHow do you think seaman found their way before modern accurate methods of navigation were invented?How did they navigate so well?early navigational instruments compass compass kmpskmpsastrolabeastrolabe strleb strleb星盘The astrolabeThe astrolabe measures the height and position measures the he

3、ight and position of the sun.From this a captain can tell where the of the sun.From this a captain can tell where the boat is in the ocean.boat is in the ocean.Sextant(六分仪)is used to measure the angle between the horizon and some object in the sky.Nautical charts(航海图)are maps of the depth of the sea

4、 and the currents of the oceans.latitude longitudeReading Fast readingWhat did people use to help sailing?nature instrumentsHow does nature help sailing the oceans?What can instruments help to do?Using celestial bodiesto plot the positionsto work out the latitudea special cloud formation indicates t

5、here is land close by(2 minutes)Careful reading(page1)Using wildlifeIf seaweed was fresh and smelled strongly,the ship was close to land.Sea birds could be used to show the way to land when it was nowhere to be seen.(1 minute)Using the weatherTo help identify the position of a stream or river whenTo

6、 direct their sailing(1 minute)Use the information to analyze the navigational skills and write the answers in your own words.1.To find the ships position at sea a sailor used _.2.A sailor knew that land was nearby if he saw_ _.3.Sailors used _ _ to increase their speed.the North Star and the sun.se

7、a currents or tides andwinds clouds,fresh seaweed,nesting birds or fog(5 minutes)Careful reading(page2)There were two methods to find longitude:1._ 2._measuring time and speedcompass and complicatedmathematical tablesWrite down the working principles of the following instruments:Bearing circle:Astro

8、labe:Quadrant:Sextant:to compare the height of the sun now with the position of the sun at midday.to compare the position of the ship in relation to some stars or the sun.a more precise form of the astrolabe,to measure how high stars are above the horizon,and compare that measurement with previous m

9、easurements.an updated version of the quadrant and so it was more accurate,to measure the angle between tow fixed pints outside the ship.What is the use of a bearing circle,astrolabe,quadrant or sextant?()A.to set the course of the ship B.to measure the position of the ship C.to measure the speed of

10、 the ship D.to tell the timeB(10 minutes)What would you do if you came across the following problems during your voyage?What would you do if:Plan of actionYou were far from land and a storm arose.You knew your latitude but didnt know your longitude.You were blown off-course.You were offshore but you

11、 needed more food and water.You wanted to keep a straight course.You were lost with no land in sight.wait till the storm is over,and then find your new position and return to your original courseuse knots to find your speed and work out your approximate longitudeuse the compass and the astrolabe,qua

12、drant or sextant to find out your position,return to your former course.follow nesting birds to shore;look for special cloud formations or fog over streams to find landuse a compassmeasure your position using the sun or stars;look for sea birds,cloud formations,fog or seaweed to show that land is nearby-Homework After class try to collect more information about sailing or navigation,sort it out and prepare to make a presentation next class.