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1、,Unit 13,Period 1,Reading,The Properties of Water,Find out as many words and phrases as possible about water properties in the text.,Skimming,polar salinity density high heat capacity ocean motion-,Water is a liquid at room temperature,and it has a relatively high freezing point.The reason why water
2、 can dissolve most substances on earth is that water has high heat capacity.Like all the other substances,water gets smaller(contract 缩小)when it freezes.Pure water has a higher freezing point and lighter than salt water.The salinity of the earths oceans is about 3.5%.When water freezes,its density i
3、ncreases.Other recourses such as oil,gas,gold etc is as precious as a drop of rain.,Quiz:True or False,Because water is polar,gets expand,decreases,Nothing is as precious as-,Find out some basic facts about life in the oceans,Scanning,Basic facts about life in the oceans from the opening paragraph:,
4、Life on earth began in the oceans about three billion years ago;99%of the living space on earth is in the oceans;There are about five million(known)species in the oceans;Life in the oceans ranges from tiny plankton to giant whales.,Life first appeared in the blue seas.,Natural selection,A diverse wo
5、rld,99%of the living space on earth is in the oceans.Why?,Because the chemical structure of water makes it an excellent medium(substance/surroundings)for life.,How many species and how rich?,Five million ranging from the tiniest plankton all the way up to giant sharks and whales.,Water is an excelle
6、nt medium for life.Why?,Water is a liquid at room temperature and has a relatively high freezing point;All living creatures need food to survive,but on many occasions the nutrients become available to living things only when they are dissolved by water.,Water is polar,it can break down both solids a
7、nd gases.Why?,Waters unique chemical structure,Oxygen Atom,Hydrogen Atom,A polar molecule,We can get a lot of nutrients by drinking soup.Plants can pull water up their roots via a capillary(毛细管)process.,Can you give some other examples which are also resulted from waters unique chemical structure?,T
8、he salinity of the earths oceans is about 3.5%.What does this mean?,There are about thirty-five grammes of dissolved solids and gases in one kilogramme of water.,In winter water in some containers or small rivers often freezes while water in seas not?Can you explain why?,The salinity of sea water ca
9、n affect the freezing point of water.Sea water has a lower freezing point,so even when the temperature of sea water falls below 0,sea water is still liquid.,What is density?,Density is the relationship between _ and _ and is measured in kg/m3,reading _.The density of water is _ kg/m3.,mass,volume,ki
10、los per cubic meter,1,000,Does the heat capacity of water also make the ocean an excellent medium for life?Why?,(a safe and comfortable habitat),The heat capacity of water is relatively _.Water can _ and _a lot of heat without big _ in temperature,_ creating a _environment.Most animalsand plants are
11、 _to large or sudden changes in _,the water in the oceans also Keeps the temperature of the earth _ by _and _heat.,high,absorb,give off,changes,thus,stable,temperature,sensitive,steady,absorbing,giving off,Whats the function of ocean motion?,Ocean motion helps move nutrients around and adds energy t
12、o the marine ecosystems.Different marine creatures live in different levels of the ocean.(Because of the foods they need,sunshine etc.),what property of water can explain the following phenomena?,The coastal areas are often neither too hot nor too cold.Ice floats on water.When the sea water in a con
13、tainer is evaporated(蒸发),there will be some salt left.Irrigate in winter can help raise the soil temperature.People swimming in the Dead Sea float;they can even read a paper while lying on their back in the water.,Waters high heat capacity,Density,Dissolvability,High heat capacity,Salinity and densi
14、ty,Your body floats on the surface of the Dead Sea,These figures show how much water there is in parts of our body!,60%70%82%90%,Up to _ of the human body is water.The brain is composed of _ water.Blood is _ water.The lungs are nearly _ water.,82%,60%,90%,70%,Water is being used for,Electricity,Agri
15、culture,Home use,Industry,Transport,Entertainment,Water is a must to life.Without water,life would not exist.,22nd,March,What should we do today and from today on to save water?,The theme for this year“Water For Life”,Water is so important that we Should value every drop of it.Do it from now on!Do it every minute!Save water!Save life!Save the earth!For human beings!For coming generations!For the future!Take action!,Try to think as many examples as possible to show that water is made use of to bring benefit to human beings.,Homework,
