Warming up、Pre-reading、Reading、Comprehending教学实录与评析

unit 2 Sailing the Ocean 1.

Lead in The four basic instruments for navigation: Sinan, Inch Astrolabe, Sextant and nautical map. It was invented by Zhang Heng in the Han dynasty. It is made up of a bronze foundation (青铜地盘) and magnetic spoon(磁勺) which is made of natural magnet, positioned right in the central of the foundation.

The handle of the spoon points to the south, while the other side points to the north. When the Sinan is in the still, the handle of the spoon points to the south because of influence of the terrestrial magnetism (地磁).

1. How do you think seamen found their way before modern accurate methods of navigation were invented? 2. Which do you think was easier to work out: latitude or longitude? 3. Can you identify these early navigational instruments seamen used and explain how they are used? 4. Which ones do you think are still used today? 2.

Read the passage and answer these questions. 1. Where do these materials come from? 2. What did the early navigator use to help them navigate? 3. What natural objects were used to assist the navigation? 4. Is it easier to measure longitude or latitude?

5. Do the astrolabe, the quadrant and the sextant mean the same thing? 3. Read the chart below and fill in your plans of action to deal with them. 4. Read the passage again and use the information to analyze the navigational skills. 1. To find the ship’s position at sea a sailor used the North Star and the sun. 2. A sailor knew that land was nearby if he saw _________________________________

_______________________. 3. Sailors used ________________________

________to increase their speed. There were two methods to find longitude:

1)_______________________

2)__________________________________

5. Write down the working principles of the following instruments:

Bearing circle:_____________________________________________________ Astrolabe:________________________________________________________

Quadrant:______________________________________________________ 6.Read the passage (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 sun’s position. 3. The quadrant was more precise and simplified than the astrolabe, but still had its shortcoming. 4. 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.

Homework 1. Review this passage. 2. Preview Learning about language.