What Makes Up an Ecosystem


Author: April Baker

Organization: Texas A&M University

Topic: Ecosystems

Grade Level: 8th

Time Frame: 50 minutes

Overview: Student created ecosystems and food web.

Purpose: The students will be able to develop a model of an ecosystem in a cooperative learning group.

National Geographic Magazines
Hunter/Fisherman Magazines
Insect Magazines
Poster Board

Getting Ready: This lesson will be the first one in a series that will go over many dimensions of the environment. For this lesson, the teacher and students need to bring magazines with various pictures of animals, insects, and vegetation. Students also need to know the differences between predators and prey, and have knowledge about the basic requirements of an ecosystem. In previous lessons, the students have been taught the definitions of autotrophic, heterotrophic, and saprotrophic organisms. This lesson will aid in future lessons having to do with food webs, primary and secondary producers, and consumers. Students must also prove previous to this lesson that they can work in- groups.

Motivate (Engage): I will ask students to think back to our field trip when we were gathering insects. I will pose the question: Imagine what would happen if the insects had no predators. Would the park change in any way? Do you think that there would be any type of major damage done to the vegetation at the park? After this series of questions, I will tell students that today it is their duty to create the perfect ecosystem. They will have to create an ecosystem with a working food chain.

Activity (Explore): Students will be given the task of creating their own ecosystem. They can include water, trees, animals, insects, and whatever else they decide to incorporate into their system. They will be working in-groups of three and everyone must agree on what makes the ecosystem work. They must label the items that can be labeled as either autotrophic, heterotrophic, or saprotrophic energy sources. All members of the groups must agree on the labels assigned to the different organisms. In addition to the labels, they must draw in pencil arrows between organisms hat feed on other organisms. (They will have a teacher given handout that gives them an example of this concept.) Direct students to also point out the energy lost between each exchange by a different shaped arrow. When they complete this task, have each group share with the class and explain why they chose and set up their ecosystem in that particular manner. When completed, use the students' ecosystems as visuals for the teacher explanation. As a group, discuss what makes up an ecosystem, the organisms that feed upon each other, and review the concepts of autotrophs, heterotrophs, and saprotrophs. During this session, students will be encouraged to take notes for an upcoming quiz. Throughout the discussion, continue to make references to predators and their prey within the systems. Students would also be asked critical thinking questions. For example: What would happen if all of the prey were to die off? How does abiotic factors effect the success of predators? What would happen if all of the predators were removed? What would occur if all insects were taken out of the ecosystem? As we move through the example ecosystems that were created, allow students to correct any errors made in labeling.

Safety Tips: There are no special safety tips for this lesson.

Concept Discovery (Explanation): Students will receive a handout of a food web and the energy and nutrient flow in ecosystems. Students will also be asked to read a portion on ecosystems and animal-insect interactions from their textbook. The Internet will also be available so that they can visit different ecosystems around the world.

Going Further: Pose questions or problems to the class such as: If all of the heterotrophs could magically make their own food, what would happen to the system? Describe in words what you think the earth would be like if no organism depended on another for food/energy. Propose a solution to the problem that would arise.

Show a short news clip of the Exxon Valdez or similar oil spill. Ask the students to discuss in-groups of three what they think would happen if something similar were to happen off the Gulf Coast. Assign students to individually write a two- page essay of their thoughts on this issue. Include the following items: what animals and insects would be lost? How would this disrupt the food chain?

Closure: To close this lesson, show a real life example of an ecosystem at work. This would be done through a short video showing progression from primary producers all the way up the chain. Ask the students to point out similarities between the one they viewed and the ones we discussed in class.

Assessment: The student made ecosystems were used as part of my teaching and would not be graded as either right or wrong. However, the students would receive a grade on their corrected product and on how well they worked in-groups. Students will be quizzed at the end of the unit over the concepts covered in today's lesson.


Language Arts:

This activity could easily be connected to language arts by allowing students to write a story about their interaction with their ecosystem. Or, they could observe a familiar system and write journal entries.

Social Studies:

Students could look at particular food chains within a specified landscape. For example, they could look at a tropical rain forest and compare it to the prairies of the central United States. In doing this, they could use their mapping skills and learn geographical concepts.

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