北师大版高二选修8教案： Unit 22 Period 13.doc

the 13th period 文化背景知识teaching goals 教学目标exchange the information of the worst disasters in history.finish unit diary.1. ability goals 能力目标 enable the students to write about what they know on board. 2. learning ability goals.学能目标 help the students learn how to assess their learning over the unit.teaching important points教学重点help students to form good habits of learning english.teaching difficult points教学难点how to improve students learning strategies文化背景知识three economic sectors for profit firms: they make and sell private goods and services. their ultimate goal is to make a profit in selling or making goods and services. the market (supply, demand, buyers, and sellers) influences their decisions. they work towards customer satisfaction. customers voluntarily pay to purchase their goods or services. they are able to give the buyer what he or she wants at the lowest cost possible (while still making a profit). they will not take on unprofitable activities. government: it provides public goods, or services that are needed by the public (national defense, parks, etc.). it can regulate the for profit firms (e.g., trust-busting, environmental requirements, etc.). it can control areas of society through taxes/fees (e.g., public schools receive funding through taxes). its focus should be on serving the needs of the nation and the people. nonprofit organizations: they can provide public goods or services needed by the public. they can provide private goods. these organizations receive trust from those receiving the service and those supporting the service. funding comes from voluntary giving of their supporters or grant funding. their main focus is to accomplish organizational goals and break even with money coming in but no profit. global warming q & a 1. what causes global warming? is it part of a natural cycle?answer: global warming is caused by the build up of gases in the atmosphere such as carbon dioxide and methane, which form a sort of blanket over the earth, trapping in heat that would normally escape the atmosphere. the leading greenhouse gas is carbon dioxide, a pollutant emitted from the burning of fossil fuels, such as coal, oil, and natural has. while it is true that there has always been some natural climate variability, the changes that are currently underway are unlike anything that has been seen before. record levels of carbon dioxide are having a far reaching change over our weather, sea levels, and climate. 2. how can global warming affect our lives?answer: global warming is sometimes referred to as the most dangerous experiment ever conceived. we do not know what the full affect of radical climate change will be on our environment, but we do know that even a modest rise of 2- 3f (1.1-1.7c) could have dramatic effects. in the last 10,000 years, the earths average temperature hasnt varied by more than 1.8f (1.0c). temperatures only 5-9f cooler than those today prevailed at the end of the last ice age, in which the northeast united states was covered by more than 3,000 feet of ice. leading scientists assert that a rise of 3 degrees would cause famine and drought and threaten millions of lives. it would also cause a worldwide drop in crops of between 20 and 400 million tons, threatening 400 million more people with famine, and put up to 3 billion people at risk of flooding and without access to fresh water supplies. few ecosystems could adapt to such a dramatic temperature change, resulting in the destruction of half the worlds nature reserves and a fifth of coastal wetlands. global sea levels could rise by more than 20 feet if the ice shelves in greenland and antarctica collapsed, which is a distinct possibility if temperatures continue to climb. droughts and wildfires will occur more often. more than a million species worldwide could be driven to extinction by 2050. 3. does the rise in the earths temperature cause more intense storms /hurricanes/ tornados here in the us? if so, how? answer: while it is impossible to blame any single event on global warming, there are several reasons to believe that global warming will create more intense storms. hurricanes are powered by warm water on the surface of the ocean. as global warming heats the surface of the water, hurricanes will increase in speed, power, and frequency. tornadoes are caused by rapidly rising amounts of heat from the lower areas of the atmosphere to higher portions of the sky. while scientists are again reluctant to pin individual storms on global warming, global warming does create greater amounts of heat in the lower portions of the atmosphere, creating more tornado-causing energy to be released into the upper atmosphere. 4. what are the largest sources of global warming pollution in the world and in the united states? answer: the us produces far more carbon dioxide than any other country in the world. according to the latest figures by the department of energy, the us produces 22% of all co2 emitted into the atmosphere, at 5,912.21 million metric tons in 2004. that is more than china, and india together (17% and 4.1% respectively), more than russia (6%), japan (4.7%), australia (1.4%) and the whole of europe put together (17.2%). in the united states, the major sources of co2 emissions stem from burning fossil fuels, like coal, natural gas, and oil. we burn coal and natural gas to produce electricity and energy for our homes, businesses, and factories, while most of the oil is burned to power transportation, planes, buses, and especially cars. however, all of the technology that produces this energy is outdated and inefficient. we can continue to live our lives by putting more efficient technology to use, and by getting more energy from clean sources, like wind and solar.5. can we curb our emissions of global warming pollution without hurting our economy?answer: absolutely. in addition to being dirty and dangerous, americas coal and nuclear power plants are wildly expensive, americas energy policy is terribly expensive, requiring large subsidies while taking a heavytoll (造成重大损失) on consumers. there have been dozens of studies which show that by investing in clean energy, such as renewable energy and energy efficiency, we can reduce our emissions of greenhouse gases while creating new jobs and saving consumers money. while many countries in europe and asia are recognizing the need to curb emissions, americas industries are being left behind. america needs policies and programs that will stimulate green power industries, we can ensure that america will once again lead the world in technology and manufacturing. and by making simple choices in the kinds of products we buy, such as compact florescent lightbulbs and hybrid cars, we can all save money and protect the environment by consuming less energy. 6. is it too late to stop global warming?answer: while it is true that global warming is already occurring and affecting the way we live, it is vital that we take steps to curb global warming pollution. if we do not begin to make the change to clean energy, the heat waves and hurricanes that we have already suffered through will become more routine and worse. thankfully, we have all the tools necessary to curb our emissions of greenhouse gases - tools like clean energy, energy efficiency, and cars that go farther on a gallon of gas. mark twain might as well have been talking about global warming when he famously remarked, everybody talks about the weather, but nobody ever does anything about it. for years we have heard so much about the causes of climate change, that weve missed the fact that there are simple, practical solutions that can slow this growing problem. technologies exist today that can cut emissions of heat-trapping gases and make a real difference in the health of our planet. and these solutions will be good for our economy, reduce our dependence on foreign oil, and enhance our energy security.you can help to reduce the demand for fossil fuels, which in turn reduces global warming, by using energy more wisely. here are 10 simple actions you can take to help reduce global warming.1) reduce, reuse, recycledo your part to reduce waste by choosing reusable products instead of disposables. buying products with minimal packaging (including the economy size when that makes sense for you) will help to reduce waste. and whenever you can, recycle paper, plastic, newspaper, glass and aluminum cans. if there isnt a recycling program at your workplace, school, or in your community, ask about starting one. by recycling half of your household waste, you can save 2,400 pounds of carbon dioxide annually.2) use less heat and air conditioningadding insulation to your walls and attic, and installing weather stripping or caulking around doors and windows can lower your heating costs more than 25 percent, by reducing the amount of energy you need to heat and cool your home. turn down the heat while youre sleeping at night or away during the day, and keep temperatures moderate at all times. setting your thermostat just 2 degrees lower in winter and higher in summer could save about 2,000 pounds of carbon dioxide each year.3) change a light bulbwherever practical, replace regular light bulbs with compact florescent light (cfl) bulbs. replacing just one 60-watt incandescent light bulb with a cfl will save you $30 over the life of the bulb. cfls also last 10 times longer than incandescent bulbs, use two-thirds less energy, and give off 70 percent less heat. if every u.s. family replaced one regular light bulb with a cfl, it would eliminate 90 billion pounds of greenhouse gases, the same as taking 7.5 million cars off the road.4) drive less and drive smartless driving means fewer emissions. besides saving gasoline, walking and biking are great forms of exercise. explore your communitys mass transit system, and check out options for carpooling to work or school. when you do drive, make sure your car is running efficiently. for example, keeping your tires properly inflated can improve your gas mileage by more than 3 percent. every gallon of gas you save not only helps your budget, it also keeps 20 pounds of carbon dioxide out of the atmosphere.5) buy energy-efficient productswhen its time to buy a new car, choose one that offers good gas mileage. home appliances now come in a range of energy-efficient models, and compact florescent bulbs are designed to provide more natural-looking light while using far less energy than standard light bulbs. avoid products that come with excess packaging, especially molded plastic and other packaging that cant be recycled. if you reduce your household garbage by 10 percent, you can save 1,200 pounds of carbon dioxide annually.6) use less hot waterset your water heater at 120 degrees to save energy, and wrap it in an insulating blanket if it is more than 5 years old. buy low-flow showerheads to save hot water and about 350 pounds of carbon dioxide yearly. wash your clothes in warm or cold water to reduce your use of hot water and the energy required to produce it. that change alone can save at least 500 pounds of carbon dioxide annually in most households. use the energy-saving settings on your dishwasher and let the dishes air-dry.7) use the off switchsave electricity and reduce global warming by turning off lights when you leave a room, and using only as much light as you need. and remember to turn off your television, video player, stereo and computer when youre not using them. its also a good idea to turn off the water when youre not using it. while brushing your teeth, shampooing the dog or washing your car, turn off the water until you actually need it for rinsing. youll reduce your water bill and help to conserve a vital resource.8) plant a treeif you have the means to plant a tree, start digging. trees absorb carbon dioxide and give off oxygen. they are an integral part of the natural atmospheric exchange cycle here on earth, but there are too few of them to fully counter the increases in carbon dioxide caused by automobile traffic, manufacturing and other human activities. a single tree will absorb approximately one ton of carbon dioxide during its lifetime.9) get a report card from your utility companymany utility companies provide home energy audits to help consumers identify areas in their homes that may not be energy efficient. in addition, many utility companies offer rebate programs to help pay for the cost of energy-efficient upgrades.10) encourage others to conserveshare information about recycling and energy conservation with your friends, neighbors and co-workers, and take opportunities to encourage public officials to establish programs and policies that are good for the environment. these 10 steps will take you a long way toward reducing your energy use and your monthly budget. and less energy use means less dep