Unit 5 A delicate world Starting out & Understanding ideas 学案 -2023-2024学年高二英语外研版（2019）选择性必修第二册

Unit 5 Period 1 Starting out & Understanding ideas 【学习目标】 Learning Objectives 1 To understand the idea that humans are part of earth’s ecosystem 2 To learn how the chaos was caused in Macquarie Island and how people tried to conserve the island, then use “cause and effect” structure to describe a story 【学习过程】 Learning activities 目标一: To understand the idea that humans are part of earth’s ecosystem Activity 1: Watch the video and answer the questions. 1 Are humans part of Earth’s ecosystems? Why? 2 In what ways can humans affect ecosystems? Answers: _______________________________________________________________________________ _______________________________________________________________________________ Activity 2: Look at the satellite images and answer the questions. 1 What is happening to the area according to the satellite images? 2 What do you think a later satellite image would show? 3 What do you think caused these changes? Answers: _______________________________________________________________________________ _______________________________________________________________________________ Background Information: The Aral Sea Crisis The Aral Sea is situated in Central Asia, between Kazakhstan to the north and Uzbekistan to the south. It was once the world's fourth largest lake, and contained 10 grams of salt per litre. The rivers flowing into the Aral Sea are the river Syr Darya from the north and the river Amu Darya from the south. In the 1960s, the two rivers were diverted away from the Aral Sea so that people could irrigate the surrounding desert region and focus on cotton production. As a result, the Aral Sea has been decreasing in size, and by 1997, it had shrunk to a tenth of its original size, splitting into four lakes. By 2009, the south-eastern lake had disappeared altogether, and the south-western lake had been reduced to a thin strip, with a salinity level of more than 110 grams per litre. This shrinking of the Aral Sea became known as “on