课 Unit4 Astronomy:The science of the stars ----How life began on the earth? 题 学 1. Learn about the origin and development of life on earth. 习 2. Master the new wor
ds and expressions in the reading passage. 目 标 情 1. Develop Ss ability of reading, listening and describing. 感 2. Develop a good habit of protecting our environment and the earth. 目 标 重 1. The key words, phrases and expressions. 点 2. The difficult sentences with noun-clauses as the subject in the text. 难 点 学 案 内 容
导 学 过 程
单词回顾 【导入】 通过 ppt 展示太阳系各行星及其名称、运转轨迹。引入地球的形成学说、相关地理 知识，演示地球上生命的起源过程。 【自主学习】 1. How old is the earth? A. About 3.5 billion years B. About 4.5 billion years C. About 5.5 billion years D. About 6.5 billion years 2. ______ of the earth surface is covered by water. A. 20% B. 30% C. 50% D. 70% 3. How many planets are there in the Solar System? A. 6 B. 7 C. 8 D. 9 4. What is the total population of humans on the earth? A. About 3.5 billion B. About 4.5 billion C. About 5.5 billion D. About 6.5 billion 5. How long does the rotation (自转) of the earth take? A. 12 hours B. 24 hours C. a month D. 365 days 6. Which continent is the smallest? A. Africa B. North America C. South America D. Oceania 7. On what day is the Earth day celebrated? A. April 22 B. May 4 C. August 21 D. November 11 8. Which ocean is the largest? A. The Pacific Ocean B. The Arctic Ocean C. The Indian Ocean D. The Atlantic Ocean
9. Which country has the largest area? A. Canada B. China C. Russia D. U.S.A
【合作探究】 1. Why was the earth different from other planets? 2. Why did the plants grow before the animals came? 3. Why is it wrong to show films with dinosaurs and people together? 4. There used to be nine planets in the solar system. Recently scientists have decided that one of them can no longer be considered a planet. Do you know the name of that planet? Do you know why they removed it? 5. What problem is caused by human beings?
课 后 反 思