PCd, BF

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Goal:

Students identify that healthy ecosystems are made up of abiotic (light, air, and water) and biotic (producers, consumers, and decomposers) components that interact to support life. 

Objectives:

Students will be able to...

  • Define and Categorize producers and consumers. 
  • Identify decomposers as a special kind of consumer. 
  • Provide an example of a food web in which each component depends on the others. 

Vocabulary:

Ecosystem, Producer, Consumer, Decomposer, Bacteria, Fungi 

Suggested Activities:

Suggested Assessments:

Look-fors to assess student understanding: 

  • Students identifying the ecosystem role of various organisms as producers, consumers, or decomposers. 
  • Students are able to explain how producers, consumers, and decomposers depend on each other. 


Possible Alternative Conceptions (and possible responses):

  • A producer is something that produces things - like humans, or worms since they produce poop for the soil
    • That's a good definition of production. When we talk about producers compared with consumers and decomposers, we are referring to a specific scientific definition: producers are organisms that make their own food and then process it internally for energy and matter.
  • Plants get their food from the soil
    • Photosynthesis is the process by which plants make their own food. Using light energy from the sun, carbon dioxide from the air is combined with water from the soil to form the food sugar. Some of the first observations children make about plants are that they grow in soil and take in water through their roots. It's a natural extension to think that plants get food from the soil. This may also be reinforced by the term used for fertilizer - plant food.
  • Food is defined only as those things that animals eat
    • Food is any substance that provides energy and nutrients to an organism. All organisms require food. Animals are consumers and eat their food. Producers do not technically "eat" their food; they make it and then process it internally. Decomposers absorb their food. This is the scientific meaning of food.
  • Plants make food for the benefit of animals
    • The food that plants make provides them with their own source of energy and matter. Even when animals are not present, plants still make food. Children might not see the "point" of a plant except as a food source for an animal. One way to get children to broaden their ideas about plant life is to engage them in plant cultivation. Take them to the garden!
  • Decomposers recycle energy
    • If decomposers recycled energy, plants would be able to survive without energy input from the sun. If you isolate a plant without light, even in soil rich with decaying matter, it will eventually die. When teaching about food chains, children are taught that nutrients (i.e. matter) are recycled. They're also taught that nutrients in food provide energy. It's reasonable that they make the (albeit alternative conception) connection that the nutrients recycled by decomposers provide energy.

Source: http://www.learner.org/courses/essential/life/session7/ideas.html

Transfer of Learning:

Are you a part of a food web? In what ways? How do you depend on Light, Air and Water to survive? How do you depend on other producers, consumers and decomposers? 

Extensions:

  • Before or after the lesson, lead an activity or discussion about LAW (Light, Air and Water) and discuss whether these are biotic or abiotic components of ecosystems. How is LAW connected to producers, consumers and decomposers?
    • For ideas about potential LAW activities, see here or here
  • In the Art Studio, create ecosystem collages with pictures cut out of magazines to depict essential components of an ecosystem. Students should include at least one example of light, air, water, producer, consumer and decomposer. If time, ask students to draw lines or arrows connecting the ecosystem components in their collage.