Uploaded by Jennifer Castro


Exploring the "Systems" in Ecosystems
In this media-rich lesson, students use a systems thinking approach to explore the components
and processes of ecosystems. They analyze both a hypothetical and a local ecosystem by
identifying abiotic and biotic components and their relationships.
Lesson Summary
In this lesson plan, students are introduced to the concept of an ecosystem, and explore how to
analyze ecosystems using a systems thinking approach. A class discussion brings out students'
ideas about ecosystems and introduces basic information about the components and
processes of ecosystems. Next, students encounter a hypothetical ecosystem and gain
experience analyzing it the way scientists do. Students then select a local ecosystem and apply
what they have learned to analyze it. Finally, students extend their understanding by
characterizing three different types of ecosystems and describing their components and
Define an ecosystem
Begin to analyze an ecosystem using a systems thinking approach
Describe the abiotic and biotic components of an ecosystem
Identify organisms within an ecosystem as producers, consumers, or decomposers
Grade Level: 6-8
Suggested Time
Four 45-minute class periods
Multimedia Resources
Analyzing an Ecosystem Flash Interactive
Biodiversity in the Dzangha-Sangha Rain Forest Flash Interactive
Coral Reef Connections Flash Interactive
Desert Biome QuickTime Video
Use these resources to create a simple assessment or video-based assignment with the Lesson
Builder tool on PBS LearningMedia.
Yellowstone Wilderness Area PDF Document
Analyzing Ecosystems PDF Document
Comparing Ecosystems PDF Document
Before the Lesson
If possible, arrange computer access so students can work in pairs or small groups.
Print and copy PDF documents for each student.
The Lesson
Part I: Introduction to Ecosystems
1. Begin the lesson by writing the word "ecosystem" on the board or on an overhead
transparency. Ask students to describe the meaning of the word. At this time, do not judge
their answers or correct misconceptions.
2. Write the following words on the board or transparency, "city, forest, aquarium." Ask
students which of these three represent an ecosystem. Guide the discussion to bring out that
all three are examples of ecosystems, and that they can be large or small and may include
humans. Explain that ecosystems are often described as a community of organisms plus the
abiotic parts of their environment. Ecosystems are also often described by the major plants
found within them (e.g., forest ecosystem).
3. Ask students to look at the word "ecosystem" on the board again. Have them focus on the
second part of the word, "system." Ask them what it might mean to look at ecosystems as a
system. Help students reach the understanding that each ecosystem is an integrated system of
components (biotic and abiotic) and processes.
4. Display the Yellowstone Wilderness Area PDF Document or an image of another wilderness
area. Explain that this photo represents an ecosystem. Ask students to list some components of
the ecosystem and write them on the board or transparency. Students will name various
plants and animals—components of the biosphere—but they may not bring up nonliving
components of the ecosystem—such as components of the atmosphere or lithosphere. If
students do not mention abiotic components, ask them what other components might play a
role. Then help students complete their list of the ecosystem's biotic and abiotic components
and explain their importance.
5. Remind students that life requires energy to exist. Ask, "What is the source of energy for this
ecosystem?" Guide the discussion to bring out that the Sun is the ultimate source of energy for
the ecosystem, and that the energy flow within an ecosystem is one of its system processes.
Then ask students to discuss how the interactions of these different organisms (components)
contribute to the energy flow (processes) within this system.
Which kinds of living things can use the energy of the Sun to make their own food?
How do other types of organisms obtain their energy?
What happens to the matter (bodies) of organisms after they die?
Guide this discussion to bring out the following:
Green plants are the only type of organism that can convert the energy of the Sun into
chemical energy (food).
All other organisms must obtain their chemical energy (food) by eating other organisms.
Some organisms obtain their chemical energy by eating the remains of dead plants and
animals. This contributes to the recycling of matter that is found in the ecosystem.
Diagramming is a powerful way for students to develop an understanding of the complex
ways in which the parts of a system interact. Ecologists can trace the flow of energy
through an ecosystem by creating a food web. For further illustration of food webs, you
might direct students to check out the Antarctic Food Web Game Flash Interactive.
Part II: Analyzing Ecosystems
6. Explain to students that they will explore a typical ecosystem and will become familiar with
the ways in which scientists describe the components and processes, or relationships, found
within the ecosystem. Give each student a copy of the Analyzing Ecosystems PDF Document.
Then have students explore the Antarctic Food Web Game Flash Interactive to learn more
about ecosystems and answer the questions posed on the handout.
7. After students have finished answering the questions on the handout, ask for volunteers to
report their findings.
8. Ask students to reflect on the ecosystem they analyzed in Step 4 and answer the following
questions in their notebooks:
What are some examples of abiotic components?
What are some examples of biotic components?
List some of the processes, or relationships, you think exist among these components.
Provide an example of a producer and a consumer.
[Optional] If time allows, ask students to provide examples of some of the other
relationships among the components: parasitism, commensalism, mutualism, and
mimicry. How might these kinds of relationships contribute to maintenance of the
What do you think might be the advantage of applying systems thinking when analyzing
an ecosystem?
When students are finished answering the questions in their notebooks, ask them to share
some of their responses to Question (f). This may be a difficult question for students to
answer, so a discussion may help them arrive at a better understanding of systems thinking.
9. Explain that although the specific components and their relationships that students
analyzed in the previous activity are unique to that ecosystem, the terms and processes are
universal and apply to all different types of ecosystems. Provide a couple of additional
examples to reinforce the similarity of these relationships from one ecosystem to another.
Then have students reflect on what they think defines an ecosystem. Who decides? Why?
Part III: Applying Knowledge
10. Instruct students to select a local ecosystem to explore and analyze. If possible, students
should visit the ecosystem to make their observations and record them in their notebooks.
This can be done as an organized class trip, or students can be asked to make their analysis
outside of class time. The following are some suggestions for how to identify an appropriate
ecosystem for analysis:
The ecosystem can be small, such as a terrarium, aquarium, or small pond.
The ecosystem can be larger, such as a wooded area near home or school.
The ecosystem can be the local community itself.
In their notebooks, students should provide a brief description of the ecosystem they
have selected.
Students should include the following during their analysis of their ecosystem:
A list of biotic and abiotic components
A list of producers, consumers, and decomposers
[Optional] A list of examples of any parasitism, commensalism, mutualism, and
A food web that shows the energy relationships between the organisms in the
11. Discuss students' analyses as a class. Ask them what other elements besides energy might
flow in an ecosystem.
Check for Understanding
Provide each student with a copy of the Comparing Ecosystems PDF Document. Then, have
students explore the Biodiversity in the Dzangha-Sangha Rain Forest Flash Interactive, Coral
Reef Connections Flash Interactive, and Desert Biome QuickTime Video. Students should
extract the information requested on the handout from each resource.
Ask students to write down in their notebooks how using systems thinking helps ecologists
understand the interrelationships of components in different ecosystems.