The Properties of Water教案

6. qs: 1) what do different densities in the ocean result in?
      －dense water sinks and less dense water is pushed to the surface. thus water in the ocean is always moving.
      2) what phenomena can this result help us explain? please give examples. (if necessary, give students some hints such as showing a picture etc.)
ocean motion helps move nutrients around and adds energy to the marine ecosystems.
different marine creatures live in different levels of the ocean. (because of the foods they need, sunshine etc.)
7. read following statement and think what conclusion you can draw? or what property does it refer to?
     it is said that a man of 60kg loses about 1l water through breath and skin evaporation (皮膚蒸發) every day. in other words, 539kcal heat is released in these two ways. if so much heat were kept in human body, it would raise body temperature by 9℃. can you imagine the result?
－water has a relatively high heat capacity and can accommodate the climate automatically. it can absorb and release a lot of heat without big changes in its temperature, thus creating a stable environment.
8. here are some more familiar phenomena.
what property of water is each of them related to?
 the coastal areas are often neither too hot nor too cold. (water’s high heat capacity)
 ice floats on water. (density)
 when the sea water in a container is evaporated (蒸發), there will be some salt left. (dissolvability)
 irrigate in winter can help raise the soil temperature. (water’s high heat capacity)
 people swimming in the dead sea float; they can even read a paper while lying on their back in the water. (salinity and density)

step5 language points
1.provide…for
e.g. the company will provide food and drink for them.
2. have an opportunity to do something
e.g. i had no opportunity to discuss the problem with her yesterday.
3.a variety of
e.g. he left for a variety of reasons.
there are a variety of patterns for you to choose from.
4. contribute to
e.g. his work has contributed to our understanding of this difficult subject.
step6. homework
try to think as many examples as possible to show that water is made use of to bring benefit to human beings.