Food Webs, Energy Flow, Carbon Cycle, and Trophic Pyramids

Serendip Studio
Type Category
Instructional Materials
This resource, vetted by NSTA curators, is provided to teachers along with suggested modifications to make it more in line with the vision of the NGSS. While not considered to be “fully aligned,” the resources and expert recommendations provide teachers with concrete examples and expert guidance using the EQuIP rubric to adapted existing resources. Read more here.



In this activity, students analyze the production and utilization of organic molecules in ecosystems. Students use pre-made cards to construct a food web for Yellowstone National Park, including producers, primary consumers, secondary consumers, decomposers, and trophic omnivores. Then, students analyze a trophic cascade that resulted when wolves were reintroduced to Yellowstone National Park.

Students learn how organic molecules move and are transformed in ecosystems as a result of the trophic relationships in food webs, photosynthesis, cellular respiration, and biosynthesis. This provides the basis for understanding carbon cycles and energy flow through ecosystems. In the final section, students use these concepts and quantitative reasoning to understand trophic pyramids.

Intended Audience

Educational Level
  • Grade 6
  • Grade 7
  • Grade 8
  • Middle School
Access Restrictions

Free access - The right to view and/or download material without financial, registration, or excessive advertising barriers.

Performance Expectations

HS-LS2-3 Construct and revise an explanation based on evidence for the cycling of matter and flow of energy in aerobic and anaerobic conditions.

Clarification Statement: Emphasis is on conceptual understanding of the role of aerobic and anaerobic respiration in different environments.

Assessment Boundary: Assessment does not include the specific chemical processes of either aerobic or anaerobic respiration.

This resource is explicitly designed to build towards this performance expectation.

Comments about Including the Performance Expectation
The lesson progression for this resource will allow the students several opportunities to engage in the concepts of food webs, the cycles of matter and the energy that flows throughout the ecosystem. Many of the activities build off the initial activity of a card sort food web of organisms that live in Yellowstone National Park. It is recommended that the teacher break up the student handout into smaller pieces that each focus on one part of the lesson sequence since the student handout is rather lengthy and may overwhelm some students. The teacher should be sure to closely review the information that is detailed in the teacher notes in order to have clear understanding while facilitating class discussions.

Science and Engineering Practices

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
The student pages give many opportunities for students to explain the relationship between organisms in Yellowstone National Park. The questions have accompanying diagrams and graphics that students can use in addition to the food web model that they have created. Students need to develop vocabulary as they work through the activity. The teacher should be sure to utilize proper vocabulary whenever they are posing questions and require the students to respond using the appropriate vocabulary. Any unfamiliar vocabulary could be listed on the blackboard as it is encountered in context, so students have access to the proper words when responding to verbal or written questions. Student responses will allow the teacher to assess student understanding of the concepts as well as use of associated vocabulary.

This resource is explicitly designed to build towards this science and engineering practice.

Comments about Including the Science and Engineering Practice
This activity allows students, in cooperative groups to develop a food web based on background information that is provided. The students may be directed to research more about the species that are included on the premade cards, if the teacher feels that will challenge the students further. Prior to groups starting their sorting and arranging, the teacher should have a class discussion about the arrows used in the model. As with most models of food webs, the arrows show the flow of nutrition/energy. The teacher may want to discuss this with the class and have students consider what the arrow represents allowing them to make a collective decision that allows the models to be consistent. Alternatively, the teacher could allow groups to design their own models however they decide and then raise the topic of arrow direction in the follow-up discussion.

Disciplinary Core Ideas

This resource is explicitly designed to build towards this disciplinary core idea.

Comments about Including the Disciplinary Core Idea
The teacher guide and student pages include explicit information on the details that are part of this disciplinary core idea. It is imperative that the teacher includes the more discrete parts of the food web that are key to the middle school level. Understanding the need for decomposers in any ecosystem to recycle nutrients works nicely with the chemistry concepts that are incorporated. Since atoms are constantly recycled, the decomposition of living things needs to be understood in order to understand the chemistry of an ecosystem.

Crosscutting Concepts

This resource is explicitly designed to build towards this crosscutting concept.

Comments about Including the Crosscutting Concept
This activity allows students to model and, subsequently, explain the cycling of matter and the flow of energy through the trophic levels of Yellowstone Park. The change in the food web when the wolves are reintroduced allows the students to see how a change in one part of a food web can affect all levels. The activity also guides students to see the chemistry that takes place allowing matter to cycle and energy to flow. The teacher needs to make sure that students gain understanding of these core ideas. It is advisable to have discussions with each cooperative group and bring up other examples of changes that may occur in the food web, assessing each student's ability to describe the effects.

Resource Quality

  • Alignment to the Dimensions of the NGSS: While this resource includes the three dimensions of NGSS, it has several parts that are not student-driven. While this could be a worthwhile activity in a lesson progression that works toward the performance expectation, the teacher will want to give students more autonomy on other activities or revise parts if this activity to be more student-centered. The Cross-cutting Concept and Disciplinary Core Ideas are included but NGSS Science and Engineering Practices should not be as guided as much as the teacher guide outlines.

  • Instructional Supports: This resource is built around the real-world phenomena of trophic levels in Yellowstone National Park. The teacher guide provides abundant information that will help any instructor with the vocabulary and concepts if they are unfamiliar or need to review the ideas. The guide uses scientifically accurate and grade-appropriate scientific information, phenomena, and representations to support students’ three-dimensional learning. The teacher guide also has numerous links to other resources that could support or enrich this activity. The lesson sequence “provides opportunities for students to express, clarify, justify, interpret, and represent their ideas and to respond to peer and teacher feedback orally and/or in written form” as the EQuIP rubric outlines. The student guide has many quality diagrams and graphics that provide visual explanation for students. The questions in the student guide are well-written and fit the needs of the activity, although the teacher may want to break the questions into smaller segments so students are not overwhelmed.

  • Monitoring Student Progress: The class and group discussions that will be incorporated into the activity will allow the teacher to formatively assess student understanding as the activity progresses. The resulting food web and subsequent iterations of the student food webs will show how student understanding progresses. Student responses to the written questions can be used formatively or summatively depending on where the activity is used in a lesson progression to meet the performance expectation.

  • Quality of Technological Interactivity: There are no technological components to this lesson.