文档介绍：课标人教实验版高三 Module 9
Unit 2
Reading
广东曾桂萍刘玉
Discuss
1. How do you think seamen found their way before modern accurate methods of navigation were invented?
Kept close to the shore, used nature such as the sun, wind, birds, tide, etc, to help them, and used some of the instruments including pass, astrolabe, etc.
2. Which do you think was easier to work out: latitude or longitude?
Latitude, because it was used to measure how far you had traveled from land on a straight line. It was discovered a long time before longitude.
3. Can you identify these early navigational instruments seamen used and explain how they are used?
1) compass ( in ancient China)
2) astrolabe
3) sextant
4) sea / nautical / marine chart
4. Which ones do you think are still used
today?
Sea charts are still used today.
Comprehending
1. Read the passage and answer the following questions.
What is the use of a bearing circle,
astrolabe, quadrant or sextant? ( )
What is the use of pass? ( )
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
A
B
2) Why are speed and time important in working out the longitude of a ship? Speed and time are important in finding out the longitude of a ship because the earth moves fifteen degrees westwards every hour. If you know your direction, speed and time, you can work out the approximate longitude or change in your position in relation to the stars.
3) Why is the position of the sun and various stars useful for working out latitude?
The position of the sun and stars are useful for working out latitude because they are fixed points in the sky and their movements in relation to the earth are already known. So they can be used to measure a ship's position.
2. Suppose you were a sea captain aiming to sail round Africa. Discuss in groups:
1) What skills would you seek in your sailors?
2) What problems would you anticipate for this journey?