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Topics covered in this program include air pollution, water pollution, waste disposal, and the need for urban planning. The Urban Explosion Lesson Plan explores these issues in more detail.


Every day of the year, tens of thousands of people move to the world’s burgeoning cities in search of a better life. Instead they find sprawling slums, massive traffic jams, chronic unemployment, regular failure of electrical and water services, strained educational and recreational facilities, and skyrocketing fuel and food costs. The uncontrolled development of the world’s major cities has led to a series of problems — air pollution, water pollution, waste disposal, housing shortages, and loss of farmland.

As the 21st century dawns, the question is how to balance economic growth with the health of Earth’s large metropolitan cities. How do these cities shelter and sustain their residents without destroying the delicate balance of the environment? The four mega-cities (cities with populations of over ten million people) profiled in the video segments are Mexico City, Shanghai, Istanbul, and New York City. Through the segments and the activities found at the end of this lesson, students will learn more about the problems facing the world’s mega-cities, possible solutions to those problems, and the need for urban planning.

National Science Education Standards: Grades 5-8

This lesson correlates to the following content standards:

Content Standard C — Life Science
Regulation and Behavior
Population and Ecosystems
Diversity and Adaptations of Organisms

Content Standard E — Science and Technology

Understanding about Science and Technology

Content Standard F — Science in Personal and Social Perspectives

Population Resources and Environment
Natural Hazards
Risks and Benefits

Content Standard G — History and Nature of Science

Science as a Human Endeavor

Learning Objectives

Students will be able to:
  • describe the environmental problems (specifically air and water pollution) created by the rapid development of urban areas
  • identify some solutions for dealing with problems caused by uncontrolled urbanization
  • explain the importance of urban development plans in dealing with cities’ environmental problems
Previewing Activities

(Note: The teacher will need to take some time to introduce and discuss the concepts and vocabulary with the students before proceeding with the rest of the lesson.)

1.  To familiarize students with the cities profiled in the program segments, use a wall map, desk map, or an atlas, and have students locate:
  1. Mexico City, Mexico
  2. Istanbul, Turkey
  3. Shanghai, China
  4. New York City, New York

After students have located the cities, begin a discussion on what they already know about each of these places. Ask them to talk about what kinds of environmental problems large cities like these might face.

2.  Introduce the following key terms to the students:

  1. ecosystem – the community of plants and animals interacting with one another and the environment
  2. infrastructure – the foundation on which economic development is based, including the transportation, communication, electrical, and water supply systems of a community, city, or nation
  3. mega-city – a city with a population in excess of ten million people
  4. pollution – the contamination of soil, water, or the air by the discharge of harmful substances
  5. rapid transit system – mass transportation which enables people to move farther and faster through a city
  6. refugee – a person who flees usually to another country to escape oppression or persecution
  7. sewage – liquid and solid waste usually carried off in sewers or drains
  8. smog – fog that has become mixed and polluted with smoke
  9. sustainability – the ability to maintain or keep from collapsing
  10. toxic – poisonous, capable of causing injury or death, especially by chemical means
  11. urbanization – growth in the portion of a population living in areas of more than 2,500 people
  12. urban sprawl– the unplanned, uncontrolled spreading of urban development into areas adjoining the edge of a city
  13. water treatment plant – facility for the chemical treatment and recycling of water

3.  Have students discuss examples of water or air pollution in their own community and what is being done to overcome these difficulties.

4.  Have students discuss whether their community has a plan for expansion.

5.  If students are in rural communities, discuss how they have been affected by the urban explosion — people leaving the farms; farm closings; young people leaving the community; and store closings in their town.

Focus for Viewing

Say…"As you watch the following video segments, look for some of the problems resulting from uncontrolled urban growth and possible solutions. These problems demonstrate the need for a plan or vision to manage urban development."

Viewing Activities

The following viewing activities offer opportunities for student discussion of a major dilemma of the 21st century — the "urban explosion." The topics in these activities could be covered in one lesson, or extended into several lessons.

Topic: Air Pollution
Say…"Our first journey takes us to Mexico City — a city pulsing with the energy of 24 million citizens, 30,000 factories, and five million cars. Mexico City is what scientists call a closed ecosystem. The focus of this segment is on the interaction of human activity with the environment, and how the results affect the quality of life. As you watch this section of the video, think about where you live, how you live, and the effect you have on your environment."

View Segment One: length 3 minutes and 56 seconds. Pause when the screen goes black.
(Visual and audio cues: Begin to play after the program title and you hear "Mexico City pulses with energy." Stop when you hear "Thousands of repair shops cater to stricter exhaust regulations and increased auto inspections.")

Post-viewing Discussion

  1. What are some of the problems Mexico City is facing today? (Answer: little wind to cleanse the air and no ocean or major rivers to exchange water and sewage)
  2. What causes the problem of smog in Mexico City? (Answers: the combination of three million cars, 35,000 factories and its geography)
  3. How do you think Mexico City might solve these problems? (Answers will vary — stricter emission standards, public transportation, etc…)
  4. Do we face any of these same problems where we live? What are we doing or what can be done to help? (Answers will vary.)

Topic: Air Pollution Solution
Say…"Next we will visit China’s richest and most important industrial city — Shanghai. Home to thousands of multi-national corporations, Shanghai is a beacon for economic opportunity. In just a decade, its population of 13 million has grown by three million. These new citizens are peasants from the countryside looking for a better life. As a result, Shanghai, like Mexico City, is facing major environmental problems. As we explore Shanghai, pay attention to how city officials are attempting to deal with one of these problems — air pollution. Think about whether or not their solution would work for Mexico City."

View Segment Two: length 2 minutes and 2 seconds. Pause when the screen goes black.
(Visual and audio cues: Start when you see people walking down a busy shopping thoroughfare and you will see three women in red coats and hear "Each day over a million people pack its sidewalks." Stop when you hear, "Above ground, new highways ease traffic congestion as well as link Shanghai with surrounding industrial and bedroom communities.)

Post-viewing Discussion

  1. What was the cause of the smog in Shanghai? (Answers: burning low-grade coal to warm homes and run factories; car emissions)
  2. How are they trying to solve this problem? (Answers: limitations on ownership of cars and stricter air quality regulations for factories)
  3. What are they doing about the traffic problem? (Answer: rebuilding the city’s infrastructure — starting with a rapid transport system such as the subway system found in cities like New York)
  4. Would these same methods work in Mexico City? Why or why not? (Answers will vary.)
  5. How about in your area?

Topic: Water Pollution
Say…"Istanbul, Turkey is an ancient city racing into the next millenium. It is one of the new mega-cities. The city’s population is estimated to be around 15 million and growing. This rapid increase in population is due in part to refugees fleeing rural poverty and violence. These new residents are arriving at the rate of 1,400 people a day, a half million a year. As a result Istanbul is facing two critical problems–a water shortage due to this rapidly growing population and water pollution caused by waste water and the city’s shipping industry.

The underground reservoirs built by the Romans which sustained the city’s water needs for over 14 centuries cannot handle this mass migration. Istanbul needs to change its water supply as well as its method for dealing with sewage and waste water. In addition, this influx of refugees has resulted in the loss of land or greenspace due to illegal housing projects to accommodate Istanbul’s newest citizens."

View Segment Three: length 4 minutes and 29 seconds. Pause when the screen goes black.
(Start when you see the back of a building with two satellite dishes and the camera pans up to a bridge crowded with cars and you hear "With little room left in the old city, people are crowding . . . ."  Stop when you hear "Today his catch is meager — a family tradition is about to disappear.")

Post-viewing Discussion

  1. What is causing Istanbul’s water shortage problem? (Answer: migration to the city)
  2. What is causing Istanbul’s water pollution problem? (Answer: a lack of sufficient waste water treatment facilities and excessive shipping traffic on the waterway going right through the middle of the city — the Bosporous Channel)
  3. How has the water pollution problem affected the fishing industry? (Answer: The catch is meager.)
  4. Do you know of any water pollution problems in your area? What do you think should be done about them? (Answers will vary.) Note: This could be an excellent opportunity for students to research local water issues.

Topic: Water Pollution Solution
Say…"Now we return to Shanghai to see how this city is attempting to solve its water pollution problems. Toxic sewer waste water and factory pollution are issues that must be addressed. Watch closely to see how this city plans to improve the quality of its drinking water."

View Segment Four: length: 1 minute and 41 seconds. Pause when the screen goes black.
(Visual and audio cues: Start when you see the Shanghai skyline and barges on a waterway and hear "Suzhou Creek is an ancient canal cutting through the heart of Shanghai." Stop when you hear "Twenty miles upstream from Shanghai where the Hungpu is less affected by industrial waste, the government remedied the problem by building a new water intake and pumping plant.")

Post-viewing Discussion

  1. How is the city of Shanghai dealing with its water pollution problems? (Answers: A series of huge tunnels are being built to collect waste water which will then be treated and flushed out to sea. A new water purification plant has been built for drinking water.)
  2. Do you know where your local waste water treatment facility is located and how it operates? (Answers will vary) Note: This may be a good field trip opportunity.

Topic: Need for Urban Planning
Say…"Finally, we visit one of the most successful mega-cities in the world — New York City. In order for a city to function successfully, there must be a plan for sheltering and sustaining its growing population without destroying the delicate balance of the city’s environment. New York City has such a plan in the form of an infrastructure that was put in place at the end of the 19th century. With a few exceptions, New York works as a unified system — one that provides for the needs of the city’s inhabitants. Serious environmental problems such as air pollution and water pollution are dealt with more efficiently through this careful planning. In a unified system, quality of life is controlled by a city’s ability to anticipate its needs and to envision a plan to cope with change. In this final segment, we can begin to understand how a mega-city works as a unified system."

View Segment Five: length 53 seconds. Pause when the screen goes black.
(Visual and audio cues: Start when you see an aerial view of New York City at night and hear "From the air, New York is like no other place on earth." Stop when you hear Robert Kennedy Jr. say, ". . . they can use natural resources more efficiently than any other social development organism.")

Post-viewing Discussion

  1. How are the lives of the people of New York City similar to those in Mexico City, Istanbul, and Shanghai? (Answer: The quality of their lives is controlled by their city’s ability to cope with change.)
  2. What sets New York City apart from Mexico and Istanbul in terms of how they deal with their environmental problems? (Answer: New York City has a vision — a plan for a unified system.)
  3. What is the importance of having a plan before starting any expansion or development? (student discussion)
Special Projects

1. Group Project: "Building a City": Have students draw or construct what they consider to be "the perfect city." Plans should include methods for dealing with environmental issues, as well as a vision for sustainable growth and development of the city.

2. Group Project: "Improving Your City": Have students develop a plan to improve the city or town in which they live. Have them highlight what changes they would make to the existing infrastructure. To obtain an "Environmental Profile" of where you live, visit the Office of Environmental Information (

3. Have students invite a representative from their local water utility to speak to the class. This could also be done as an individual interview. Have students prepare questions such as: Where does our water come from? Where is the waste from factories and plants released? How is our local sewage treated, and where is it released? To learn more about the effects of urbanization on water, have your students visit the U.S. Geological Survey’s Water Science for Schools site at

4. Have students research the development of their community in terms of land use. Have them look at questions such as how the land was first used, and how it is used today. Have them compare and contrast the benefits of development due to population growth. Students can check with their local Chamber of Commerce, city government or Planning and Development Commission.

5. For students interested in conservation, help them get involved in a local conservation project. These projects might include planting trees, cleaning up riverbeds or beaches. To discover other project ideas, check out "Fun Activities" at the Environmental Protection Agency's Student Center (

6. Throughout history, storytelling has been an important tool for learning about the past. Have students write a myth or legend about population growth and its effects on the environment. They may want to include such ideas as the uncontrolled growth of Earth’s population, and the effects on the Earth, the oceans and the skies. Encourage them to be creative.


Internet Sites

EE-Link (Environmental Education on the Internet)
This site’s mission is to spread information and ideas that will help educators explore the environment and investigate current issues with students.

Environmental News Network
The mission of this network is to create environmental awareness on critical issues through the presentation of fair and balanced daily news and information products.

EPA Curriculum and Resources
Resources for teachers on topics ranging from conservation, air and water pollution to waste and recycling are found here.

EPA Student Center
At the student center, youngsters in the middle and high school grades can explore a wide range of environmental issues–from air and water pollution and ecosystems to waste and recycling.

Global Action Center
The Global Action Center provides current information on world activities in areas including air, water, climate and habitat.

Urbanization and Water Quality
The U.S. Geological Survey’s Water Science for Schools site examines the effects of urbanization on water quality.

Water Environment Federation
Water Environment Web provides a database for examining the leading companies and suppliers serving the water environment community, as well as student materials and activities (K-12) concerning the water environment.

Agencies and Organizations

CARE International
660 Fifth Avenue
New York, NY 10016
(212) 686-3110
Good source of information on agencies that deliver relief assistance to people in need and on long-term solutions to global poverty.

680 Mount Auburn
Box 403
Watertown, MA 02272
(617) 926-8200
An organization whose mission is to build a sustainable future through partnerships between scientists and citizens.

Friends of the Earth
218 D Street S.E.
Washington, DC 20003
(202) 783-7400
Dedicated to protecting the planet from environmental degradation, Friends of the Earth is a good source for student reports and information for awareness of urbanization issues.

Greenpeace USA
1436 U Street NW
Washington, DC 20009
(202) 462-1177
This is the leading independent environmental organization that uses peaceful and creative activism to protect the global environment.

Population Reference Bureau, Inc.
1875 Connecticut Avenue N.W., Suite 520
Washington, DC 20009
(202) 483-1100
This is a source of information on specific statistics on population and population growth.

Sierra Club
530 Bush Street
San Francisco, CA 94108
(415) 776-2211
Students can request information on the Club’s efforts to protect the environment against problems caused by urbanization.

U.S. Agency for International Development
State Department Bldg.
2201 C Street NW
Washington, DC 20520
(202) 634-3600
This is a source of information on urban development in the United States and in countries around the world.

The United Nations Environment Programme
Rm. DC2-0816
United Nations
New York, NY 10017
(212) 963-8138
Source for information on the environment as it is affected by the population growth and/or urbanization of cities.

World Affairs Council
1726 M Street N.W. #800
Washington, DC 20036
(202) 293-1051
Another source for information on the environment as it is affected by the population growth and/or urbanization of cities.


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