上册 Unit 51Unit 5Text A Can We Know The Universe- Reflections on a Grain of SaltTeaching Objectives（教学目的）（教学目的） Students will be able to 1. grasp the main idea and structure of the text 2. master the key language points and grammatical structures 3. conduct a series of reading, listening, speaking and writing activities related to the theme of the unit.Teaching procedures（教学步骤）（教学步骤） (1) Pre-reading activity （Period1） a. Information related to the text b. Introduction to the Text c. Pre-reading questions (2)While-reading activity（Periods2-3） a. The organization of the text b. Detailed reading-study of the language points (3) Post-reading activity （Period4） a. Speaking Activity b. Writing Practice c. Have students finish the exercises Period 1 Pre-reading activity a. Background Information 1. Introduction to the AuthorAmerican astronomer and pioneer exobiologist. Sagan was born in New York city and studied at the University of Chicago, where he received a Ph.D. in astrophusics. Sagans research wsa directed toward evidence of life in outer space. He also studied the origins of organism with geneticsts Hermann J. Mullers and Joshua Lederberg. 2. Introduction to the Text The Bi Bang Theory Big Bang Theory, currently accepted explanation of the beginning of the universe. The big bang theory proposes that the universe was once extremely compact, dense, and hot. Some original event, a cosmic explosion called the big bang, occurred about 10 billion to 20 billion years ago, and the universe has since been expanding and cooling. The theory is based on the mathematical equations, known as the field equations, of the general theory of relativity set forth in 1915 by Albert Einstein. In 1922 Russian physicist Alexander Friedmann provided a set of solutions to the field equations. These solutions have served as the framework for much of the current theoretical work on the big bang theory. American astronomer Edwin Hubble provided some of the greatest supporting evidence for the theory with his 1929 discovery that the light of distant galaxies was universally shifted toward the red end of the spectrum (see Redshift). 上册 Unit 52This proved that the galaxies were moving away from each other. He found that galaxies farther away were moving away faster, showing that the universe is expanding uniformly. However, the universes initial state was still unknown. In the 1940s Russian American physicist George Gamow worked out a theory that fit with Friedmanns solutions in which the universe expanded from a hot, dense state. In 1950 British astronomer Fred Hoyle, in support of his own opposing steady-state theory, referred to Gamows theory as a mere “big bang,” but the name stuck. Indeed, a contest in the 1990s by Sky there will be no source of motivation for the thinking being if ervery thing is known or if the unverse is unknowable.b. Detailed reading-study of the language points Detailed reading of the text Purposes：To help students draw important facts of each paragraph To help students identify and remove the source of difficulty in understanding the 上册 Unit 54text To help students actively interact with the text and develop strategies to work out themeaning of the textTo give students practice in note-takingMethodology：When working through the text, you can, besides explanation (refer to “Detailed Explanation of the Text in the students book), use the technique of asking questions to develop students understanding. Make sure students always keep their text open when they answer the questions. The purpose of asking questions is to make students actively interact with the text and develop their strategies to derive the meaning from the text. At the same time, they can become aware of the way language is used to convey meaning. There is a close connection between answering questions and developing understanding.At the start, three types of questions should be designed for this purpose. First, straightforward questions need to be asked to draw students attention to important facts in the text and to ensure they understand the literal meaning of the factsThe second type of questions should be used to develop students skills of tackling difficult sentencesA third type should make students recognize grammatical and lexical features that play a crucial part in the interpretation of the text When students answer your questions they should also practice taking notes. You can ask the following questions orally.1. What are the goals of science? Can we rely on our intuition or perception to achieve these goals? 2. What are the bases of scientific study of the world around us? 3. What does “Just So Stories” mean in para 2? Can we count on explanations divorced from experiment, or from carful comparative observations? 4. What are the characteristics of a scientifi