Threats to Biodiversity: Why We Should Care
Teacher’s Guide
Grade Level: 6-8
Curriculum Focus: Life Science
Lesson Duration: Two class periods
Program Description
Threats to Biodiversity: Why We Should Care—Earth displays a dazzling variety of life-forms, but
many of these organisms are disappearing. The main reason is destruction of habitats by human
activity. This program argues for preserving biodiversity, using several case studies as examples.
In Central America, jaguars and scarlet macaws are among many species threatened by the trade
in exotic pets, as well as by habitat destruction. Frog species disappear at an alarming rate all over
the world. Oceans are being depleted of fish. Destruction of some keystone species has damaged
entire biomes. Ancient giants such as African elephants and California redwoods are severely
threatened. The program explains how the loss of biodiversity also threatens humans and
describes efforts of conservationists to preserve species and their habitats.
Discussion Questions
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What is biodiversity?
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What trends or activities are threats to biodiversity?
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Why is it important to maintain biodiversity?
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What methods are people using to maintain and restore biodiversity?
Lesson Plan
Student Objectives
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Define biodiversity and explain why it is important to people and their environment.
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Identify at least three causes of the decrease in biodiversity on Earth today.
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Write a case study of biodiversity in your community, state, or region.
Materials
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Threats to Biodiversity: Why We Should Care video
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Computer with Internet access
Threats to Biodiversity: Why We Should Care
Teacher’s Guide
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2
Print resources about biodiversity, including textbooks, encyclopedia articles, and maps and
other materials from local government agencies and environmental groups
Procedures
1. Alert students that the program uses a case study approach. Explain that case studies are
specific examples that illustrate general trends. Encourage them to note details from each case
study and to compare the case studies. This comparison will enable them to draw general
conclusions.
2. After students have viewed the program, ask them to define biodiversity (a condition in which
there is a large variety of plant and animal species). Have students recall details about the case
studies presented in the program. Encourage students to compile comparison tables as they
summarize and to circle or group elements that the cases have in common. The program
presents the following details:
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Macaws and jaguars: Both animals are native to Central American tropical rain forests.
Macaws are large, brightly colored relatives of parrots. In the wild, they fly. They make
their nests in mangrove swamps and feed in rainforests. Poaches capture many of these
birds to sell as exotic pets. Habitat destruction is another major reason these birds are
threatened. Jaguars are large cats. They are solitary animals that meet other jaguars only
to mate. They are hunted for their beautiful fur and threatened by habitat destruction.
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Disappearing frogs: There are many frog species. All species are disappearing at rates
that alarm scientists. The draining of wetlands and the destruction of other habitats are
the major threats. Scientists also blame air pollution and are studying how the increase
in ultraviolet radiation caused by the destruction of the atmosphere’s ozone layer is
affecting habitats.
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California sea otters: Their habitat is the coast of California from Los Angeles to San
Francisco. Unlike seals, otters have no layer of blubber, so they must eat constantly to
stay warm. They are a keystone species. They feed on sea urchins, which would
otherwise destroy the offshore kelp beds altogether. Hunted for their dense, waterproof
fur, sea otters almost disappeared by the early 1900s. The species is now protected, but
its habitat is still threatened.
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Oceans without fish: Just 50 years ago fish still seemed an infinite resource. Now,
however, fish are disappearing from all of Earth’s oceans. The main reason is
overfishing, made possible by bigger and better fishing boats. In some places, such as
Newfoundland and New England, commercial fishing has been limited in order to
replenish the stock. The limits have put many fishermen out of work.
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Elephants in Africa: Elephants live in large herds that are dominated by the oldest
female elephants. They pass on social behavior to their offspring. A century ago there
were about 20 million elephants in Africa; today there are about 600,000. Big game
hunting for sport, poaching for ivory, pressure from population growth, and habitat
reduction are the major threats to elephants.
Published by Discovery Education. © 2005. All rights reserved.
Threats to Biodiversity: Why We Should Care
Teacher’s Guide
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Coastal redwoods: They are hundreds of feet tall and hundreds of years old. Some trees
have been alive since the time of the Roman Empire. Redwood forests once covered
millions of acres, but 95 percent of the original forest has been destroyed. The trees
produce valuable timber that is in high demand for its durability. Sustainable forestry is
one solution being tried to preserve these ancient trees and jobs in the timber industry.
3. Ask students to consider the human element in declining biodiversity. Students may express
their ideas in class discussion or in short essays. Students should identify threats to biodiversity
that are common to one or more of the program case studies, such as illegal hunting and habitat
destruction. Students should also explain the importance of biodiversity and how it can be
maintained. Encourage different points of view.
4. Have students use print and Web resources to learn more about biodiversity. Suggest that
students visit the Web sites of local and state governments, especially parks, conservation, and
environmental departments. Encourage students to locate threatened natural resources near
you. Web sites of environmental groups also contain valuable information. The following Web
sites are good starting points:
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PBS: Bill Moyer’s Reports: Earth on the Edge: Ecosystems
http://www.pbs.org/earthonedge/ecosystems/index.html
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American Museum of Natural History: Biodiversity: Everything Counts!
http://ology.amnh.org/biodiversity/index.html
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U. S. Environmental Protection Agency: Kids Club
http://www.epa.gov/kids/
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Franklin Institute Online: Living Things (Select “Neighborhoods.”)
http://sln.fi.edu/tfi/units/life/
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The Globe Program
http://www.globe.gov/globe_flash.html
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Healthy Forests (Select your state.)
http://www.healthyforests.gov/
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Jefferson Lab: Science Vocabulary Hangman (Select topics under “Biology and Living
Systems.”)
http://education.jlab.org/vocabhangman/
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Missouri Botanical Garden: Biomes of the World
http://mbgnet.mobot.org/
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NASA’s Earth Observatory: Life (Select topics from left column.)
http://earthobservatory.nasa.gov/Topics/life.html
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National Atlas: Environment
http://nationalatlas.gov/environment.html
Published by Discovery Education. © 2005. All rights reserved.
Threats to Biodiversity: Why We Should Care
Teacher’s Guide
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National Oceanic and Atmospheric Administration (NOAA) Photo Library: Sanctuaries
http://www.photolib.noaa.gov/sanctuary/index.html
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National Park Service: Nature and Science (Select “Biology.”)
http://www2.nature.nps.gov/
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National Park Service: Web Rangers
http://www.nps.gov/webrangers/
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NatureWorks (New Hampshire Public Television): Nature Files (Select general topics
from “Concepts” in left column and specific animals from right column.)
http://www.nhptv.org/natureworks/nw4.htm
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PBS: American Field Guide (Select “Ecosystems.”)
http://www.pbs.org/americanfieldguide/
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University of California Museum of Paleontology: The World’s Biomes
http://www.ucmp.berkeley.edu/glossary/gloss5/biome/index.html
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U. S. Environmental Protection Agency: Global Warming Impacts
http://yosemite.epa.gov/OAR/globalwarming.nsf/content/ImpactsHealth.html
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U. S. Fish and Wildlife Service Student Page (Select “Endangered Species” and
“Habitats.”)
http://www.fws.gov/educators/students.html
5. When students have completed their initial research, ask them to work individually or in teams
to research and write case studies relevant to biodiversity issues in your region. For example,
students might write about a species that is disappearing from your environment. Students
should identify reasons for the problem and outline possible solutions.
6. Ask students or teams to share their case studies with the class, in oral or written form. The case
studies may also be reproduced and distributed in notebook form. Encourage interested
students to follow through on local issues.
Assessment
Use the following three-point rubric to evaluate students’ work during this lesson.
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3 points: Students were highly engaged in class discussions; followed directions accurately;
produced accurate case studies, including all of the requested information; and described in
detail a local threat to biodiversity.
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2 points: Students participated in class discussions; followed most directions; produced
adequate case studies, including most of the requested information; and described a local
threat to biodiversity.
Published by Discovery Education. © 2005. All rights reserved.
Threats to Biodiversity: Why We Should Care
Teacher’s Guide
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1 point: Students participated minimally in class discussions; created incomplete case
studies with little or none of the requested information; and did not identify or describe a
local threat to biodiversity.
Vocabulary
adapt
Definition: To change in a way that increases the chances of survival and reproduction
Context: Different species of frogs have adapted to a wide variety of environments.
biodiversity
Definition: Containing a large variety of plant and animal species
Context: The expansion of human activity is the biggest reason for the decline in biodiversity.
camouflage
Definition: Appearance or behavior that allows an organism to hide against its background
Context: A jaguar’s spots and a tree frog’s bright green color are examples of camouflage in
nature.
captive breeding
Definition: Conducting a program to mate wild animals in a controlled setting in order to raise
their young and save their species
Context: A captive breeding program in Central America is trying to save the macaws.
cataclysm
Definition: A catastrophe or disaster of large dimensions
Context: The destruction of the rain forest is a cataclysm for the species that live there.
chlorofluorocarbons (CBCs)
Definition: A group of chemicals that break down Earth’s ozone layer
Context: Air conditioners and refrigerators are common sources of pollution from CBCs.
clear-cutting
Definition: Cutting down an entire section of forest at once
Context: Commercial timber operations often involve clear-cutting and then replanting forests.
conservationist
Definition: A person dedicated to preserving and saving the environment
Context: Conservationists are trying several approaches to preserving biodiversity.
depleted
Definition: Drained or stripped of resources
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5
Threats to Biodiversity: Why We Should Care
Teacher’s Guide
Context: Over 95 percent of California’s giant redwood forests have been depleted.
kelp
Definition: An offshore underwater plant that grows in thick formations
Context: Underwater forests of kelp provide food and protection for many marine animals.
keystone species
Definition: A species whose presence or absence has a great impact on the surrounding
environment
Context: California sea otters are a keystone species because they help preserve the kelp forests.
old-growth forest
Definition: A forest formed entirely by nature, without human intervention
Context: Most of North America’s old-growth forests have now disappeared.
ozone
Definition: A highly reactive form of oxygen that forms a protective layer in the upper
atmosphere
Context: In recent years scientists in Antarctica have been measuring a hole in the ozone layer.
poacher
Definition: A person who illegally captures wild or tame animals
Context: Consumer demand for exotic pets has increased the number of poachers, even in
protected areas.
reserve
Definition: A large area set aside for the refuge and protection of wild animals
Context: The nation of Kenya in Africa depends on tourism to finance its nature reserves.
second-growth forest
Definition: A forest that grows up where previous forests have been cleared
Context: A second-growth forest has much less biodiversity than an old-growth forest.
voracious
Definition: Excessively greedy, especially for food
Context: Sea urchins are voracious consumers of kelp.
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6
Threats to Biodiversity: Why We Should Care
Teacher’s Guide
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Academic Standards
Mid-continent Research for Education and Learning (McREL)
McREL’s Content Knowledge: A Compendium of Standards and Benchmarks for K–12 Education
addresses 14 content areas. To view the standards and benchmarks, visit
http://www.mcrel.org/compendium/browse.asp.
This lesson plan addresses the following national standards:
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Science—Life Sciences: Understands relationships among organisms and their physical
environment; Understands biological evolution and the diversity of life
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Language Arts—Viewing: Uses viewing skills and strategies to understand and interpret
visual media
National Academy of Sciences
The National Academy of Sciences provides guidelines for teaching science in grades K–12 to
promote scientific literacy. To view the standards, visit this Web site:
http://books.nap.edu/html/nses/html/overview.html#content.
This lesson plan addresses the following national standards:
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Life Science: Populations and ecosystems; Diversity and adaptations of organisms
Support Materials
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Credit
Judith Conaway, curriculum writer, editor, and instructional designer
Published by Discovery Education. © 2005. All rights reserved.