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6-8 > Ecology
Grade level: 6-8 Subject: Ecology Duration: Two class periods
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Students will understand the following:
1. The threat to water ecosystems is a complex problem because many factors contribute to their pollution and destruction.
2. The following factors all play major roles in the pollution and destruction of water ecosystems: PCBs, DDT, metylmercury chloride, sewer sludge, thermal effluents, radioactive wastes, destruction of marshlands, and beach erosion.
3. Methods to combat the above factors exist.
4. More methods are being developed and need to be developed.

For this lesson, you will need:
Research materials about water ecosystems and factors that contribute to their pollution or destruction
Computer with Internet access

1. Ask students to name some water ecosystems. (They might mention oceans, rivers, ponds, lakes, marshlands.)
2. Now ask them to mention any factors they know of that contribute to the pollution and destruction of water ecosystems. List their suggestions on the chalkboard, including the following: PCBs, DDT, metylmercury chloride, sewer sludge, thermal effluents, radioactive wastes, destruction of marshlands, and beach erosion.
3. Divide your class into groups, and have each group research one of the factors you have listed. Groups should focus their research on how their factor affects water ecosystems, particularly those in your area, if applicable, and the methods that are being employed to counter it.
4. When their research is complete, each group should choose one water ecosystem that has been affected by the factor they have been assigned and prepare an environmental-impact statement about it. Each statement should include four elements:
  1. a description of the current environmental status of the ecosystem
  2. a description of the way or ways in which the factor affects the ecosystem
  3. a description of the existing methods that are being used to combat the factor
  4. suggestions for future methods of combating the factor
5. When the statements are complete, invite groups to share their findings with the class.
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Adaptations for Older Students:
Have students include a scientific explanation for how and why the factor they have been assigned contributes to the pollution and destruction of the ecosystem on which their statements focus.
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Discussion Questions

1. Discuss the relationship between population growth, advances in technology, and ocean dumping.
2. Discuss the ways in which the traditional uses of the ocean are changing.
3. Explain how toxic substances such as DDT, PCBs, and mercury enter the ocean and become incorporated into food chains.
4. Brainstorm “environmentally friendly” ways of generating electricity, cleaning up wastewater, producing fuel, and developing land.
5. Discuss alternatives to ocean dumping to prevent further contamination of wildlife habitats and commercial seafood.
6. Discuss why there must be international cooperation concerning oil drilling, fishing, and radioactive waste disposal for the ocean to be useful to the whole world.
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You can evaluate your students on their assignments using the following three-point rubric:
  • Three points:complete description of the current status of the ecosystem, accurate description of the way or ways in which the factor affects the ecosystem, clear description of methods being used to combat the factor, reasonable suggestions for future methods
  • Two points:adequate description of the current status of the ecosystem, acceptable description of the way or ways in which the factor affects the ecosystem, vague description of methods being used to combat the factor, unrealistic suggestions for future methods
  • One point:vague description of the current status of the ecosystem, unsatisfactory description of the way or ways in which the factor affects the ecosystem, inadequate description of methods being used to combat the factor, no suggestions for future methods
You can ask your students to contribute to the assessment rubric by determining how many suggestions for future methods should be included.
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One Family’s Trash
Collect the solid wastes that accumulate in your home during a given week, and then bring them into class. Divide the class into groups; then give each group one bag of wastes. Ask each group to separate the wastes in their bag into separate categories and place them in new bags—one for all metals; one for glass, plastics, and rubber; one for paper; and one for organic materials. Make sure that they use rubber gloves when handling the waste. When the trash has been sorted, they should weigh the collected materials in each category. Each group should combine its results with those of the other groups, and then determine the waste type per member of your household per day (weight of each bag/number of residents of the house/7). Students can then extrapolate to determine how much waste each member of your family generates in each category in a given year. Students can then analyze the data, creating a pie chart to illustrate what they’ve discovered. Which types of waste are most prominent and why? If there are 250 million United States residents, what is the total amount of waste generated nationwide in a year, assuming that your family is representative of the general population? Finally, challenge the students to develop a variety of alternative uses for these discarded “resources”—other than recycling. (Example: Sandals have been made from old rubber tire treads.)

An Ideal Home
Ask your students to use their imaginations to design an ideal home that is as eco-friendly as possible. How many rooms would they include for a family of four? How big would those rooms be? How would the house be heated and cooled? What appliances would they have? What materials would they build their house out of? How would they recycle and reuse their waste products? Each student should create a detailed drawing of their ideal eco-friendly home with descriptive labels explaining each of the house’s special eco-friendly features. The students can then post their drawings around the room and examine each other’s work. Conclude the lesson with a discussion of the merits and drawbacks of the various designs.

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Suggested Readings

Ocean Planet: Writings and Images of the Sea
Peter Benchley. Harry N. Abrams and Times Mirror Magazines in association with the Smithsonian Institution, 1995.
Fabulous full-page colored photographs and illustrations make these essays on the oceans and the problems facing them come alive. Read about “ghost nets,” a “dead zone,” bat stars, gentoo penguins, and dangers to coral reefs. You’ll find a list of organizations that help our “ocean planet” and a detailed list of what others have done to preserve our oceans.

The Greenpeace Book of Water
Klaus Lanz. Sterling Publishing Co., Inc., 1995.
In this fabulous book, colored photos and illustrations depict the role that water has played in the lives of people and all living things throughout history. The book also examines the pollutants that are contaminating our waters. Read about what’s threatening our planet’s oceans and what you can do to help.

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Turning the Tide on Trash
A learning guide on marine debris maintained by the EPA.

Athena: Curriculum Oceans
A wonderful collection of activities and lessons on the ocean as well as other science topics. Its goal is to promote an interest in science and technology.

Major Oceanic Surface Currents
An interesting site maintained by the Los Alamos National Laboratory that clearly identifies the ocean currents for student research.

A great resource for teachers and students maintained by the several Canadian marine facilities that includes lesson plans, current events, and ask a scientist forums.

Bridge: Ocean Science EducationTeacher Resource Center
A wealth of teacher resources and materials on marine science that is well organized and frequently updated by The Virginia Institute of Marine Science.

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Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    biodegrade
Definition:To break down, especially into innocuous products, by the action of living things.
Context:Plastics and fuels biodegrade more rapidly when they come from crops.

speaker    petrochemicals
Definition:A commercially used chemical derived from petroleum or natural gas.
Context:We can use crops as substitutes for petrochemicals.

speaker    synthetic
Definition:Produced by artificial processes.
Context:Much of what we make employs synthetic molecules that never existed in nature before we created them.

speaker    toxic
Definition:Acting, or likely to act, as a poison.
Context:Humans are devastating the seas with toxic chemicals.

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This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
Grade level:6-8
Subject area:science
Understands the interactions of science, technology, and society.
Knows that technological solutions have intended benefits and unintended consequences; some consequences can be predicted, but others cannot.

Grade level:6-8
Subject area:science
Understands basic features of the Earth.
Knows the processes involved in the water cycle (e.g., evaporation, condensation, precipitation, surface runoff, percolation) and their effects on climate patterns.

Grade level:6-8
Subject area:science
Understands the scientific enterprise.
Knows ways in which science and society influence one another (e.g., scientific knowledge and the procedures used by scientists influence the way many individuals in society think about themselves, others, and the environment; societal challenges often inspire questions for scientific research; social priorities often influence research priorities through availability of funding for research).

Grade level:6-8, 9-12
Subject area:science
Understands the cycling of matter and flow of energy through the living environment.
Benchmark 6-8:
Knows how energy is transferred through food webs in an ecosystem (e.g., energy enters ecosystems as sunlight and green plants transfer this energy into chemical energy through photosynthesis; this chemical energy is passed from organism to organism).

Benchmark 6-8:
Knows how matter is recycled within ecosystems (matter is transferred from one organism to another repeatedly and between organisms and their physical environment; the total amount of matter remains constant, even though its form and location change).

Benchmark 9-12:
Knows that the amount of life any environment can support is limited by available resources, energy, water, oxygen, and materials and by the ability of ecosystems to recycle the residue of dead organic material.

Grade level:9-12
Subject area:science
Understands the nature of scientific knowledge.
Knows that from time to time major shifts occur in the scientific view of how the world works, but usually the changes that take place in the body of scientific knowledge are small modifications of prior knowledge; change and continuity are persistent features of science.

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Lisa Lyle Wu, biology teacher at Thomas Jefferson High School for Science and Technology and freelance editor and writer.
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