1、Unit 4 AstronomyPre-reading.1. The origin of life on earth is a question that interests astronomers. What do you know about it? How old is the universe? (several billion years ago) How old is the Earth? (between 4.5 and 3.8 million years ago) Which were the first creatures or plants on Earth2. Each

2、religion and culture has its own ideas about how life began on earth. What do you know? In China, we all know that Pangu separates the sky from the earth.Questions:1. What do we mean when we say we are studying a subject scientifically? Or whats the correct attitude towards science?We should be obje

3、ctive, not superstitious.2. Whats the correct way to prove a scientific idea? We should design experiments to test it for several times. Then we can analyze the results and draw a conclusion at last.3. What are the most important skills we need to be real scientists? Careful, objective and logical,

4、draw conclusions from the experiments and not impose conclusions on the data. (imposeon 把強(qiáng)加于)ReadingI. Read the passage carefully and analyse its structure. Write down the main idea for each paragraph.Para1 A widely accepted theory about the formation of the universe Para2 The formation of the earth

5、 Para3 The importance of water for life Para4 The development of plants and animals on the earth Para5 The arrival of humans and their impact on the earthII. Read the text and fill in the blanks in the following form. TimeWhat happenedBig Bang_ began to form and combine to create stars and other bod

6、ies.Between 4.5 and 3.8 billion years agoDust settled into a solid and _ globe.The earth exploded to produce its_ .The continued _ of water allowed the earth to dissolve harmful gases and _ into the oceans and seas.Many millions of years laterThe first small plants on the surface of the water produc

7、ed_ .Early _ and all sorts of fish appeared.Green plants began to grow on land. Insects and_ appeared.IV. True (T) or False (F).1. The earth appeared before the Big Bang happened.2. The original atmosphere consisted of nitrogen and oxygen. 3. Water also appeared on other planets like Mars, but it disappeared later. 4. Life began in water and then on land.5. Mammals appeared before the development of dinosaurs. How life began on earth is one of the biggest puzzles