Unit 13 The Water Planet教案

unit 13 the water planet
period 1  reading
teaching goals:
1. to get the ss to understand the main properties of water by connecting them with some common phenomena and learning to explain the phenomena.
2. to enable them to be aware of the importance of water, making good use of water in a proper way and protecting water resources.
teaching steps:
step1: lead in
read a short poem and guess its name: a letter from _______. (water)
dear user,
shame to you all, the ignorant,
i am your life
but you seem not to value me
give me all the respect
for in me is eternal life
if you continue abusing me
surely, all forms of life will wither away
have you ever imagined,
life without me?
i tell you, it will be unbearable
think twice
for every drop counts...
qs: 1) what does “dear user” here refer to?
2) what does it talk to its users?
3) on which planet does it exist?  －on the earth, which is also called the water planet.
4) do you know why it is called “the water planet”?
－because about three quarters of the earth is covered by water.
step 2: pre-reading
look at the titles in the text below. do not read the whole text. pick out the subject of each paragraph. use the structures below to make six questions related to the subjects.(p.19)
step 3: while reading:
1. skim to find basic facts about life in the oceans from the opening paragraph:
  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.
2.quiz: true or 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 縮小) 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.
8)  there are about five billion species in the oceans ranging from the tiniest plankton to giants like sharks and whales. (billion --- million)
9)  the water molecule is made of two hydrogen atoms and one oxygen atom.             10)  pure water has a higher freezing point and is lighter than salt water. (made of --- made up of)