The Properties of Water教案

what can ________ be compared to?
how does _______ work?
what are some examples of ________?
skim to find the words and phrases which describe the properties of water in the reading text.
scan to find out some basic facts about life in the oceans.
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.
t: yesterday you were required to ask more questions about water’s properties and find out the detailed information about water properties as well. so now let’s have a little quiz about the properties of water.
true of false questions:
1) water is a liquid at room temperature, and it has a relatively high freezing point.
2) the reason why water can dissolve most substances on earth is that water has high heat   capacity.
3) like all the other substances, water gets smaller (contract) when it freezes.
4) pure water has a higher freezing point and lighter than salt water.
5) the salinity of the earth’s oceans is about 3.5%.
6) when water freezes, its density increases.
7) other recourses such as oil, gas, gold etc is as precious as a drop of rain.
(tfftt ff)
step4. while-reading
as we all know, charles darwin is famous for his “the origin of species”. (according to his theory of evolution)
qs: 1) was there any life on the earth billions of years ago?
    2) if any, what was the original life like at that time?
    3) where did it live?  －in the deep blue seas.
    4) how does the world take its shape, which is quite different from what it used to be, especially those various organisms? －billions of years’ natural selection.
2.it is said that 99% of the living space on earth is in the oceans.
qs: 1) what does this fact result in?    －marine life is incredibly rich and varied.
2) can you give some specific numbers or examples?
－there are about five million species in the oceans. they range from the tiniest plants all the way up to giants (e.g. sharks and whales).
3) what does this fact imply? do you agree?
 －water is an excellent medium for life.
4) why do you agree that water is an excellent medium for life? (based on common knowledge)
 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.