Chapter One
Human Issues
Activity 1: Population-More Is Less 2
Activity 2: Food? What Food? 18
Activity 3: We "Auto" Drive Less 27
Activity 4: Toxics in the Home 41
Activity 5: Wants and Needs 52
Activity 6: What''s Happening? 64
Activity 7: Think Globally, Act Locally 75
Activity 8: Do It! 86
Activity 1 Population-More Is Less
Activity Summary
Students calculate what happens to a population that increases (or decreases) exponentially at varying rates. They see what effect population changes have on per capita availability of finite resources. They then consider whether increased population would have a positive or a negative effect on various environmental factors. Finally, they imagine themselves living forty years from now and write a letter to their imaginary grandchild.
Content Standard Alignment
This activity can help students meet the following National Science Education Standards put forth by the National Research Council.
Grades 5-8
Content Standard C: As a result of their activities in grades 5-8, all students should develop an understanding of
Populations and ecosystems
Content Standard F: As a result of their activities in grades 5-8, all students should develop an understanding of
Personal health
Populations, resources, and environments
Risks and benefits
Grades 9-12
Content Standard C: As a result of their activities in grades 9-12, all students should develop an understanding of
Interdependence of organisms
Matter, energy, and organization in living systems
Content Standard E: As a result of their activities in grades 9-12, all students should develop:
Understandings about science and technology
Content Standard F: As a result of their activities in grades 9-12, all students should develop an understanding of
Personal and community health
Population growth
Natural resources
Environmental quality
Natural and human-induced hazards
Science and technology in local, national, and global challenges
Content Standard G: As a result of their activities in grades 9-12, all students should develop an understanding of
Science as a human endeavor
Introduction
The issue of overpopulation is THE overriding environmental issue of our time. As population increases, more stress is put on the Earth''s finite resources. As people endeavor to raise their standards of living, even more stress is put on the Earth. An understanding of population dynamics is crucial to understanding our environmental problems and possible solutions.
One aspect of the population issue is the simple magnitude of the numbers involved. As death rates have decreased, the human population has increased exponentially. In some areas, mainly in the more developed countries, this growth has slowed as resources have been depleted, people have learned the importance of slowing or stopping population growth, and birth control methods have become available. In Europe, the population was growing by only 0.3 percent annually in 1990. By 2006, Europe''s natural population growth rate (not counting immigration) was actually -0.1 percent (fewer people were being born than were dying.) The 1996 natural growth in the United States was 0.6 percent. In other areas, though, the population has been growing much more rapidly as medical and agricultural advances have combined to reduce death rates and increase fertility. Africa''s annual growth rate in 2006 was 2.4 percent, while Latin America''s was 1.5 percent. Although those percentages may not seem large, exponential growth results in very large increases in just a few years. Today there are about three births for each death worldwide. Part I of this activity is intended to demonstrate graphically the results of exponential growth in population and the possible results of exponential population reduction.
In Part II of this activity, the students consider the consequences of rapid population growth. Open space, clean water, adequate food supplies, and other characteristics of a desirable and healthy environment become much more difficult to obtain and maintain as the population increases. Generally, increased population results in more pollution, depletion of natural resources, crowding, stress, and other undesirable developments. We need to consider not only the quantity of life, but the quality of life.
Finally, in Part III, the students consider what the future might be like if population continues to grow at its present rate. At the current rate of growth, the Earth''s population will double in less than forty years. Few demographers expect, though, that the Earth will be able to sustain such rapid population growth. The results of such growth are impossible to predict with accuracy, but there certainly will be major changes in all aspects of the human experience.
Grouping
Parts I and II: twelve approximately equal teams
Part III: individuals
Time
Part I: 30-50 minutes
Part II: 20-40 minutes
Part III: 20-40 minutes, or as homework
Anticipated Outcomes
The students will
Understand the effect of exponential growth on populations
Increase their understanding of the relationship between population and resources
Know the meanings of the terms on the vocabulary list
Consider the effect of increased human population on the environment
Materials
Photocopied student pages:
1.1 Population-More Is Less: Background Information (one per student)
1.2 Population-More Is Less: Instructions, Parts I and II (one per team)
1.2 Population-More Is Less: Instructions, Part III (one per student)
1.3 Population-More Is Less: Questions (one per student)
For each team:
1 red, 1 green, and 1 black pen, pencil, or crayon
1 calculator
Graph paper
13 apples, candy bars, large soft cookies, or other easily cut food
Knife
Overhead transparency of Instructions sheet (1.2), Parts I and II, and graph paper
Colored pens for writing on transparencies
Optional: overhead transparency of Instructor''s Data Sheet (1.4)
Vocabulary
birth rate
carrying capacity
death rate
demography
doubling time
emigration
exponential growth
immigration
per capita
population
Teacher Preparation
1. Photocopy the Background Information sheet (1.1), Instructions sheets for Parts I, II, and III (1.2), and Questions sheet (1.3).
2. Obtain the materials.
3. Make overhead transparencies of the Instructions sheets (1.2), Parts I and II, and graph paper.
4. Optional: Make a transparency of the Instructor''s Data Sheet (1.4).
Procedure
Part I: Exponential Growth
1. Ask the students whether they think that, forty years from now, when they have their own families, they will have a better, worse, or the same lifestyle as they and their parents do now. Discuss the meaning of "better lifestyle."
2. Ask the students whether they think the world''s population is increasing, decreasing, or is stable. Tell them that it is increasing.
3. Ask the students what relationship there might be between population and lifestyle. Discuss finite resources and introduce the term per capita.
4. Ask the students how fast they think the world''s population is increasing, both as a percentage and as a number per year.
5. Distribute the Background Information sheet (1.1). Have the students read it.
6. Discuss the Background Information sheet with the class.
7. Distribute the Exponential Growth Instructions sheet (1.2), Part I. Discuss the assignment with the students.
Be sure they know how to use the calculators and round off numbers to the nearest whole number.
If necessary, help them determine how to make their graphs.
8. Assign each of the teams one of the following growth rates:
0.5% 1.0% 1.5% 2.0% 2.5% 3.0% -0.5% -1.0% -1.5% -2.0% -2.5% -3.0%
9. Allow about twenty to thirty minutes for the students to do their calculations and graphs.
10. Make an overhead transparency of the data, project it, and discuss it.
11. Give each team an apple (or soft cookie or candy bar). Cut out (or add) part of it proportional to the population change over the twenty-year time period, depending on the growth rate they calculated. (See the following calculations.) Discuss how the apple represents any finite resource, such as food, water, land, or minerals. Discuss the effect that various population growth rates have on the amount of the resource per capita.
Part II: Quality or Quantity?
1. Distribute the Instruction sheet 1.2 (Part II: Quality or Quantity?).
2. Explain the assignment to the students.
3. Have the students do the assignment in teams of two to four, possibly the same teams that worked together for Part I.
4. Discuss the results of the activity.
Part III: Dear Grandchild
1. Distribute the Instruction sheet 1.2 (Part III, Dear Grandchild) and explain the writing assignment.
2. After the students have completed the assignment, discuss their realizations and feelings.
Discussion
Part I
1. Were you surprised at how rapidly the population changed with only a small rate of growth?
2. How can a country''s birth rate decline yet its population increase?
3. Distinguish between a reduced rate of population growth and a reduced population.
4. How might population increases in the more developed countries affect your life 10, 20, 30, or 40 years from now?
5. How might population increases in the less developed countries affect your life 10, 20, 30, or 40 years from now?
6. How might population increases in your local area affect the lifestyle there in 10, 20, 30, or 40 years from now?
Part II
1. Did the "good" things (green) tend to increase or decrease with increased population?
2. Did the "bad" things (red) tend to increase or decrease with increased population?
Part III
What were some of your thoughts as you wrote your letter?
Answers to Worksheet 1.3
1. As a population increases exponentially, there is an ever-increasing rate of growth, resulting in a steeper and steeper population growth curve.
2. Generally, increased population results in a decrease of things that we consider desirable and an increase of most undesirable things. Refer to students'' activity sheets for examples.
3. It is not possible for the entire world to live as we in the United States do. If 4.3 percent of the population of the world uses 30 percent of the resources, each 1 percent use 30-4.3, or about 7 percent of the resources. Thus, for 100 percent of the world to use an equivalent amount, they would use 700 percent of the resources! (Another way to look at this is to point out that each of us in the United States use about seven times as much as the average person on Earth. To be fair, we should cut our resource consumption to about one-sixth or one-seventh of what it currently is. How do the students feel about that?)
4. Answers will vary, but it is very important for population growth to be halted in all areas.
5. Answers will vary.
6. Answers will vary.
7. Generally, an increase in human population will result in:
a. More extinctions.
b. Lower quality of air and water, at least until technology catches up with growth (IF it does).
c. Less space available.
d. Less food available per capita.
e. More stress and conflict as competition for resources increases.
f. Less energy per person.
g. More competition for jobs and housing.
h. More chance of spread of contagious disease due to crowding.
i. Answers will vary, but there will probably be less freedom and fewer resources available.
j. Answers will vary.
8. Answers will vary. Some nations already do.
9. Answers will vary. Some nations already do.
10. Answers will vary. Students should address both their own family size and their use of resources. (If it is not comfortable for you, it''s not necessary to get into a discussion of HOW to control family size. You might discuss why many people feel that they should do so.)
Extensions
(See Activities 7, "Think Globally, Act Locally," and 8, "Do It!" for student project ideas.)
Part I
1. Obtain copies of the latest U.S. or World Population Data Sheet from the Population Reference Bureau, or view it online. They also publish activity guides to go with their data sheets.
Population Reference Bureau 1875 Connecticut Avenue, NW, #520 Washington, DC 20009 (800) 877-9881 www.prb.org
2. Have students study the writings of Thomas Malthus, Paul Ehrlich, and other writers on population issues.
3. Have the students graph their prediction of what would happen to resources per person on the same graph as their exponential population change graph.
4. Invite guest speakers on population issues including:
a. Ways of preventing pregnancy, including abstention
b. Abortion
c. Women''s rights
d. Resource distribution
(Some of these topics are controversial. Be sure to check your district''s policies regarding controversial issues. Also, be sure to screen speakers carefully. They can sometimes do more harm than good.)
5. Have students make a bulletin board of a graph of the human population through time, including projected population for the next hundred years. It can be illustrated with pictures from magazines, the Internet, or drawn by students.
Part II
1. Discuss the role of technology in the population resources question.
2. Have the students make a bulletin board of the arrows from this activity, illustrated with pictures from the Internet, magazines, or drawn by students.
Part III
1. Have the students write a letter to a friend or grandchild as if it is forty years from now and the world''s population is reduced-through peaceful humane means-by 50 percent from today''s population. Compare this scenario to that of the letter with doubled population.
2. Have students make a bulletin board depicting the idea that the United States has about 4.3 percent of the world''s population but uses about 30 percent of the world''s energy and mineral resources and produces about a third of the world''s pollution and trash. (That''s a pretty big slice of the pie!)
Modifications
Part I
1. Students can reduce or extend their computations and graphing as far as you wish. To correlate with Part III, you might have them carry them out to forty years.
2. Have one team calculate a very high growth rate, such as 7 percent or more.
Part II
Add other factors, both good and harmful.
Part III
Have the students write a letter to a classmate who is currently their friend, imagining that they haven''t seen each other for forty years. They should describe the changes in their environment and living conditions.
Internet Connections
Population Connection (formerly Zero Population Growth) has several population education resources available for teachers: www.populationconnection.org
Population Reference Bureau publishes an annual World Population Data Sheet both online and in print format: www.prb.org
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Excerpted from Environmental Science Activities Kitby Michael L. Roa Copyright © 2009 by John Wiley & Sons, Inc.. Excerpted by permission.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
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