Unit4 Globalwarming
教學過程step 1 warming up1.warming up by reading and talking：read through the exercise with the class.put students in groups of four to talk about what we use energy fo r，what are the sources of these energy and whether the sources are renewable or non－renewable.suggested answer：the six photos are：windmills；a coal power station；an oil refinery；a nuclear power plant；solar panels；a hydro－electric dam.2.warming up by discussion：draw a form on the blackboard as follows：
things that use energy
sources of energy
renewable/non－renewable
let the students have a discussion and collect suggestions from students and write them under the appropriate heading.suggested answer：
things that use energy
sources of energy
renewable/non－renewable
lights
heating
television
cassette player
video recorder
computer
fridge
stove
hairdryer
...
coal
non－renewable
oil
non－renewable
natural gas
non－renewable
wind power
renewable
solar energy
renewable
nuclear energy
non－renewable
hydro－electric power
renewable
biomass energy
renewable
geothermal energy
renewable
tidal energy
renewablestep 2 pre－reading1.show a picture of a greenhouse to students and ask them what a greenhouse is made of and what its purpose is.suggested answer：it's made of glass and plants can grow in it when it's cold outside.
ask the students how it works.suggested answer：the glass traps the heat from the sun，making the air warm so that plants grow better.2.ask students what they think “greenhouse gases” are and what they think greenhouse gases do.look at the picture above and explain it to their partners.suggested answer：greenhouse gases perform the same function as the glass in a glasshouse：they trap the heat of the sun and keep the air surrounding the earth warm.this is called the greenhouse effect.)step 3 reading and comprehending1.fast readingask students to read the passage quickly so as to get the key words and general idea of each paragraph and answer the following questions：(1)what is the main topic of the article?________________________________________________________________________(2)who wrote the magazine article？what is the name of the magazine?_____________________________________________________________ ___________(3)what are the names of the three scientists mentioned in the article？do they agree with one another?________________________________________________________________________