Compost food web

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By first doing a scientific drawing of a macro-invertebrate and then identifying the organism, students will identify which trophic level their macro is a part of using the compost food web hand out and gain an understanding of how energy and matter flow in a compost ecosystem.


Students will be able to:

  • Identify the source of matter and energy for different organisms in an ecosystem
  • Describe multiple connections between organisms and factors in an ecosystem


  • Have students identify which trophic level the organism that they drew belongs in, and how it depends on other biotic and abiotic factors in the ecosystem for its survival. 
  • Draw a food web with annotations on the arrows that explain the connections

Age Group: 4-7th

Venue: any

Time: 45 minutes

Materials: Compost Food Web Sheets, soil, microscopes or lumiloops, journals, pencils

The Lesson Plan


"Good soilis absolutely teeming with life. . . . A mere teaspoon of good garden soil, as measured by microbial geneticists, contains a billion invisible bacteria, several yards of equally invisible fungal hyphae, several thousand protozoa, and a few dozen nematodes."
[A]n acre of good garden soil teems with life, containing several pounds (about 1 kilogram) of small mammals; 133 pounds of protozoa; 900 pounds each of earthworms, arthropods, and algae; 2000 pounds of bacteria; and 2400 pounds of fungi.
Remember that teaspoon of good garden soil? Perhaps 20,000 to 30,000 different species make up its billion bacteria--a healthy population in numbers and diversity." -Lewis and Lowenfels in Teaming with Microbes 
  • Today, we have an opportunity to look more deeply at the roles of at least one of these organisms, and examine their role in their ecosystem, as well as figure out where their energy comes from. 


  1. Students choose one macro from their soil sample that they would like to do scientific drawing of.
  2. After students have finished their scientific drawings, labeling and including as many details as possible, handout identification keys or direct students to page 18 in their Student Field Journals. 
  3. Once they have identified their organism, students should write the name of the macro on their scientific drawings. 
  4. Hand out the compost food web handouts (found in either the wet lab or the garden greenhouse) and have students work with a partner to describe what the handout is depicting. Ask them to try to figure out what the different numbers and arrows represent on the handout.
  5. Once they have figured out that they are looking at a food web, ask the students to help you draw a food web on the white board that they are already familiar with. Example: Plant>rabbit>coyote>decomposer>plant (This straight line is an example of a food chain rather than a web but several chains can be joined to create a web)
  6. Compare and draw connections between the food web that you have drawn on the board and the one on the handout.
    • Which way does energy flow in each of the examples?
    • Are there producers, consumers and decomposers in each one?
    • What are the organisms on the third level eating? Does that make them producers, consumers, or decomposers?
    • What about the organisms on the first level? Second level?

Example Compost Food Web

Food web of the compost pile.jpg

Relevant Journal Pages

  • Common Soil Organisms p. 18
  • Ecosystem Inputs and Outputs p. 4
  • Things and Roles in an Ecosystem p. 5

Additional Resources: