unit 9 saving the earth
1．brief statements based 0n the unit
in this unit，ss will do some listening speaking，reading and writing practice．also, they will learn to use the inversion．in the first period，ss wi1l improve their speaking ability by talking about nature ecology and the environment and they will listen to some listening material about our environment．after the study of this period，they will improve their speaking and listening abilities and also know something about the problems facing the earth．in the second period，ss will read a passage about the earth summit．from the passage ss will know more about the importance of protecting our earth．in the third period．ss will study the grammar item：inversion．after doing some exercises provided in this period．and with the help of the teacher，ss will know how to use the inversion．teacher may provide more exercises for ss to consolidate if necessary．in the last period，ss will listen to two speeches from the earth summit and finish the practice provided in the first part．ss will know more about the earth summit and improve their listening ability．in the writing part, ss will improve their writing ability by writing an evaluation paragraph with the help of some given expressions．after the study of this unit．ss will know how to support an opinion，and they will know more about environment protection．they will know that if all of us make small changes．we could make a big difference．they will do more to protect our earth．
ii．teaching goals
1．talk about nature ecology and the、environment．
2．practise supporting an opinion．
3．learn to use inversion．
4．write an evaluation paragraph．
iii．teaching time：five periods
iv．background information
1．protect the ozone layer
in the middle of winter，when snow is falling in many parts of the united states,
scientists have sounded a warning to people who plan to spend many hours in the sun this summer．the warning：the sun"s summer-time rays are more dangerous than once
thought．
a team of scientists from 80 nations recently reported to the united nations that a layer of ozone in the atmosphere, which protects humans from harmful levels of ultraviolet radiation，will be thinner over the united states this summer．the thinner 1ayer allows more ultraviolet rays from the sun to reach the earth．the extra amount of ultraviolet radiation could cause an increase in the number of cases of skin cancer．
scientists first became concerned about the ozone layer in the mid-1980s when a hole was discovered in the layer above antarctica during the winter．the hole was caused by chemicals used in refrigerators and air conditioners．when these chemicals are sent out into the atmosphere, they produce gases that destroy the ozone．
