Warmingup、Pre-reading、Reading、Comprehending.ppt

1、Unit 2 Sailing the oceans,Teaching aims Let students have some knowledge of early navigation methods. train the students reading ability. Inspire students to explore more about ancient travelling after class.,Zheng He,Christopher Columbus,Ferdinand Magellan,Do you know them?,we call them sailors or

2、navigators,How 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 kmps,astrolabestrleb,星盘,The astrolabe measures the height and position of the sun. From this a captain can tell where

3、 the 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 and the currents of the oceans.,latitude,longitude,Reading,Fast reading,What did people use to help sailing?,nature,instruments

4、,How does nature help sailing the oceans?,What can instruments help to do?,Using celestial bodies,to plot the positions,to work out the latitude,a special cloud formation indicates there is land close by,( 2 minutes ),Careful reading (page1),Using wildlife,If seaweed was fresh and smelled strongly,

5、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 weather,fog,To help identify the position of a stream or river when,To direct their sailing,( 1 minute ),Use the information to analyze the navigational skills and write

6、 the answers in your own words.,To find the ships position at sea a sailor used _. A sailor knew that land was nearby if he saw_ _. Sailors used _ _ to increase their speed.,the North Star and the sun.,sea currents or tides and,winds,clouds , fresh seaweed,nesting birds or fog,( 5 minutes ),Careful

7、reading (page2),There were two methods to find longitude: 1. _ 2._,measuring time and speed,compass and complicated,mathematical tables,Write down the working principles of the following instruments:,Bearing circle: Astrolabe: Quadrant: Sextant:,to compare the height of the sun now with the position

8、 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 measurements.,an updated version of the quadrant and so it was more accur

9、ate, 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 the ship D. to tell the time,B,( 10 minutes ),discussion,Wha

10、t would you do if you came across the following problems during your voyage?,wait till the storm is over, and then find your new position and return to your original course,use knots to find your speed and work out your approximate longitude,use the compass and the astrolabe, quadrant 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 land,use a compass,measure your position using the sun or stars; look for sea birds, cloud formations, fog or seaweed