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1、UNIT2 Sailing the oceansQuestion:How many oceans are there in the world?Pacific OceanAtlantic OceanIndian OceanArctic Oceanthe Arctic Oceanthe Indian Oceanthe Pacific Oceanthe Atlantic OceancompassAstrolabe(星盘星盘)Sextant(六分仪六分仪)sea/nautical chartearly navigational instrumentsRead about what navigatio
2、n was like before modern instruments were used.Sailing the oceansFast-reading How did seamen explore the oceans before latitude and longitude made it possible to plot a ships position?Page 1Using nature l Keeping alongside the coastlinel Using celestial bodiesl Using wildlifel Using the weatherl Usi
3、ng the seaUsing celestial bodiesto plot the positionsto work out the latitudea special cloud formation indicates there is land close byUsing 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.Usi
4、ng the weatherTo help identify the position of a stream or river whenTo direct their sailing 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
5、used _ _ to increase their speed.the North Star and the sun.sea currents or tides andwindsUsing nature clouds,fresh seaweed,nesting birds or fog Fast-reading What skills did sailors use to explore the seas and discover new lands?Page 2Using navigational instruments 1.Finding longitude 2.Finding lati
6、tudethe compassl the bearing circle (方位圆方位圆)l the astrolabe (星盘星盘)l the quadrant (象限仪象限仪,四分仪四分仪)l the sextant (六分仪六分仪)Read again and fill in the blanksThere were two methods to find longitude:1._ 2._measuring time and speedcompass and complicatedmathematical tablesUsing instruments Read the passage(
7、Reading)and decide whether the following statements are true(T)or false(F).1.An early method of calculating longitude was to use a knotted rope tied to a log.2.The astrolabe was the first instrument to measure the suns position.3.The quadrant was more precise and simplified than the astrolabe,but st
8、ill had its shortcoming.TFT4.Up till now,the most accurate and reliable navigational instrument is the sextant.5.The astrolabe,quadrant and sextant are different kinds of navigational instruments and they have nothing to do with each other.F FConsolidation.We may want to know(1)_seamen explored the
9、oceans(2)_ latitude appeared.(3)_they didnt have the modern navigational help,seamen could still control the sea by using some skills to explore seas and discover the new lands.(4)_(use)nature is the first and most useful form of(5)_(explore),such as using celestial bodies,using wildlife,using the weather,and using the sea.Because of these skill,sailors increased the ability(6)_ navigate new seas when they used instruments,(7)_ (include)longitude and latitude.howbeforeThoughUsingexplorationtoincludingHomework1.Review new words.2.Finish the Exercises.of unit4