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(共25张PPT)
Unit7 The natural world
Reading
The earth’s main ecosystems
What ecosystems（生态系统） can you see in the video
Watch a video
oceans
wetlands
forests
Let's explore（探索） the three magic lands of the Earth—oceans, wetlands and forests.
skimming
What type of text is the article
A. expository text (说明文)
B. argumentative text (议论文)
C. narrative text (记叙文)
D. descriptive text (描述文)
Where can we read this kind of article
A. In a story book
B. In a travel guide
C. In a geography magazine
An ecosystem includes all the living and non-living things in an area. Ecosystems can be of different sizes, from small ponds to large grasslands. Each ecosystem has a role to play and helps keep the balance between all its members and the greater environment.
The ocean is a very large ecosystem on earth. It covers around 71% of the earth’s surface and produces about 70% of the earth’s oxygen. It holds plenty of salt water, and the water rises to the sky, falls onto the lands and then returns to the ocean. This goes on and on, so the ocean is just like the “heart” of the earth.
Wetlands only cover about 6% of the earth’s land area. But they are home to about 40% of all the types of plants and animals. Plants in wetlands help get rid of pollution and make the water clean. Wetlands can also help prevent floods. During heavy rains, wetlands store water like huge sponges. They act like the “kidneys” of the earth.
Forests make up nearly a third of the earth’s land area. Plants there take in carbon dioxide from the air and produce oxygen.They also trap harmful things in their leaves and help clean the air. Therefore, people often call forests the “lungs” of the earth.
Each of these ecosystems supports millions of plants and animals. They keep the planet healthy and make our world a better place.
Read for structure（结构）
How many paragraphs（段落） are there
What's the structure of the text
总 分 总
Read for structure（结构）
Part 1
Part 2
Part 2
Part 2
Part 3
Part 1
Part 2
wetlands
forest
Part 3
the importance of ecosystems
the meaning of an ecosystem
ocean
introductions to three ecosystems
What’s the main idea of each part
Read for structure（结构）
What is an ecosystem
An ecosystem includes all the___________________________and__________________________________________ work together.
living things (plants
non-living
& animals)
things (air, water and
sunlight)
Read for details
Part1:the meaning of an ecosystem
Is this an ecosystem
√
√
×
Read for details
Part1:the meaning of an ecosystem
Careful-reading
Ecosystem Nickname（昵称） Size/Coverage（大小） Function（功能）
Oceans
Wetlands
Forests
Watch and find
Ecosystem Nickname（昵称） Size/Coverage（大小） Function（功能）
Oceans
Wetlands
Forests
"heart"
"kidneys"
"lungs"
around 71%
about 6%
nearly a third
watch and find
Careful-reading
What does the ocean do for the earth？
Read for details
Part2:an introduction to the ocean ecosystem
How could the ocean support the water cycle（水循环）
_____
_____
_____
______
E.hold
A.rise to
C.fall onto
B.return to
D.go on and on
Beginning
v. 容纳
不停，周而复始
Read for details
Part2:an introduction to the ocean ecosystem
Which ones of the following do the wetlands do
清除; 摆脱
/pr vent/v. 防止；阻止
/st (r)/vt. 贮存=hold water
/sp nd / n. 海绵块
A. Get rid of pollution.
B. Make the water clean
C. Help prevent floods
D. Store water like sponges.
E. Help clean the air
F. Trap harmful things
G. Home to plants and animals
A. Get rid of pollution.
B. Make the water clean
C. Help prevent floods
D. Store water like sponges.
E. Help clean the air
F. Trap harmful things
G. Home to plants and animals
A. Get rid of pollution.
B. Make the water clean
C. Help prevent floods
D. Store water like sponges.
E. Help clean the air
F. Trap harmful things
G. Home to plants and animals
A. Get rid of pollution.
B. Make the water clean
C. Help prevent floods
D. Store water like sponges.
E. Help clean the air
F. Trap harmful things
G. Home to plants and animals
A. Get rid of pollution.
B. Make the water clean
C. Help prevent floods
D. Store water like sponges.
E. Help clean the air
F. Trap harmful things
G. Home to plants and animals
Read for details
Part2:an introduction to the wetland ecosystem
2.Plants also produce harmful things in their leaves and help clean the air. ( )
/tr p/ vt. 吸收；使落入险境
1.Plants produce carbon dioxide and take in oxygen. ( )
3.Forests make up nearly one third of the earth’s land area. ( )
T
Write a T if a sentence is true or an F if it is false.
1.Plants take in carbon dioxide and produce oxygen. ( )
F
2.Plants also trap harmful things in their leaves and help clean the air. ( )
F
Read for details
Part2:an introduction to the forest ecosystem
While-reading
Ecosystem Nickname（昵称） Size/Coverage（大小） Function（功能）
Careful reading
produces oxygen（氧气）
water cycle（水循环）
home to plants and animals
clean water
prevents（阻止） floods
produce oxygen
trap（吸收） harmful things
clean the air
Oceans
Wetlands
Forests
"heart"
"kidneys"
"lungs"
around 71%
about 6%
nearly a third
Why are these ecosystems so important
Read for details
Part3:the importance of ecosystems
Further-thinking
Write down the names of ecosystems
oceans
forests
wetlands
The earth is just like the “heart” of the earth.
Wetlands act like the “kidneys” of the earth. People often call forests the “lungs” of the earth.
The ocean covers around 71% of the earth’s surface.
What writing skills are used in these sentences
A. Give numbers（列数字） B. Similes（明喻）
( )
( )
A
B
The ocean covers around 71% of the earth’s surface.
The earth is just like the “heart” of the earth.
Wetlands act like the “kidneys” of the earth. People often call forests the “lungs” of the earth.
more vivid（生动）
more accurate（精确）
easy to understand
Why ？
Further-thinking
What other ecosystems do you know about
desert
grassland
mountain
Further-thinking
What other ecosystems do you know about
rainforest
coral reef
What can we do to protect these ecosystems
1.plant more trees
2.reduce pollution
3.don’t throw waste everywhere
4. ...
5. ...
Further-thinking
Homework
Choose another ecosystem and write some sentences to introduce it, use the skills (similes and give numbers) learnt today.
Must do
Choose to do
Retell the article according to the mind map
Explore more ecosystems！
Post-reading
Retell the passage
Thank You

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