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Ecosystems | Lesson 5 - Ecosystems Applications and Unit Posttest

Lesson 5: Ecosystems Applications and Unit Posttest

Students use computer software to look at different ecosystems, discuss a video about where food comes from, listen to a song about biosynthesis in a food chain, and then take the unit posttest.

Guiding Question

How does carbon cycling apply to real-world situations?

Activities in this Lesson

  • Activity 5.1: (Optional) Ecosystem Services and Carbon in Ecosystems (40+ min)
  • Activity 5.2: (Optional) Energy and Matter in Food Webs (20 min)
  • Activity 5.3: How Ecosystems Matter (45 min)
  • Activity 5.4: Ecosystems Unit Posttest (20 min)


This lesson includes culminating activities and a unit posttest that address all of the unit objectives.

NGSS Performance Expectations

Middle School

  • Matter and Energy in Organisms and Ecosystems. MS-LS2-4. Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.
  • Earth’s Systems. MS-ESS2-1. Develop a model to describe the cycling of earth’s materials and the flow of energy that drives this process.

High School

  • Interdependent Relationships in Ecosystems. HS-LS2-2. Use mathematical representations to support and revise explanations based on evidence about factors affecting biodiversity and populations in ecosystems at different scales.
  • Matter and Energy in Organisms and Ecosystems. HS-LS2-5: Develop a model to illustrate the role of photosynthesis and cellular respiration in the cycling of carbon among the biosphere, atmosphere, hydrosphere, and geosphere.

Background Information

Students consider several real world situations to apply their understanding of ecosystems and carbon cycling. Thinking about real-world situations will help students practice their knowledge and help students understand the relevance of this topic.

Activity 5.1 helps students consider how land use choices affect carbon pools: Some choices have the effect of moving carbon from the atmosphere into organic matter pools; other choices have the opposite effect. Students also examine carbon pools in various ecosystems other than meadows.

Activity 5.2 helps students consider one of the many ways in which actual ecosystems are more complicated than the simplified models they used in this unit—detritus-based food chains. The models in the unit described herbivores and carnivores as getting all their food directly or indirectly from living plants. In fact, there are many small animals such as earthworms and pillbugs that eat decomposers—bacteria and fungi living on the organic matter in soil carbon. Humans, too, are sometimes part of detritus-based food chains, as when we eat mushrooms, carnivorous fish, or free-range chickens.

Activity 5.3 provides an opportunity for students to review what they have learned about ecosystems (matter cycles while energy flows, ecosystems can support more producers than herbivores than carnivores, and disturbances change ecosystems) and apply it to three local ecosystems of their own choosing.

Activity 5.4 includes the unit posttest. As you look at your students’ responses to the posttest questions, consider how well their answers reflect their progress toward understanding ecological matter cycling and energy flow, and answering the Large Scale Three Questions for a variety of ecosystems. See Lesson 5.4: Grading Ecosystems Unit Posttest for assistance in interpreting your students’ responses.

Key carbon-transforming processes: Cellular Respiration, Photosynthesis.