课前准备：
阅读文章，完成小试牛刀的问答题。
教师导引：阅读文章，理清文章结构，上网搜寻有关人类探寻宇宙的资料，以帮助文章理解。
小贴士：联系个人的生活，谈一谈自己有哪些向外探寻挑战的经历？它们给你留下了哪些思考？
小试牛刀
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How much do you know about the earth?
参考答案：
Earth is the third planet from the Sun and the only astronomical object known to harbor life. According to radiometric dating and other sources of evidence, Earth formed over 4.5 billion years ago. Earth's gravity interacts with other objects in space, especially the Sun and the Moon, Earth's only natural satellite. Earth revolves around the Sun in 365.26 days, a period known as an Earth year. During this time, Earth rotates about its axis about 366.26 times.
Earth’s atmosphere has no definite boundary, slowly becoming thinner and fading into outer space. Three-quarters of the atmosphere's mass is contained within the first 11 km (6.8 mi) of the surface. This lowest layer is called the troposphere. Energy from the Sun heats this layer, and the surface below, causing expansion of the air. This lower-density air then rises and is replaced by cooler, higher-density air. The result is atmospheric circulation that drives the weather and climate through redistribution of thermal energy.
学习目标
By the end of the class, students will be able to
1. Understand the general ideas and detailed information of the passage;
2. Solve your own questions about the passage;
3. Master the vocabulary, phrases and grammar of the passage;
4. Know how to be a good language leaner.
知识结构
进入学习任务
