Exploring Energy Pyramids

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Objective

SWBAT Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.

Big Idea

Students explore the flow of energy in ecosystems through analysis of energy pyramids.

Engage

5 minutes

In this section of the lesson I engage students by showing the TEDEd video Dead Stuff: The secret ingredient in our food chain by John C. Moore.  This video introduces students the the concept of energy flow in ecosystems. (MS-LS2-3. Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem.)  

When you picture the lowest levels of the food chain, you might imagine herbivores happily munching on lush, living green plants. But this idyllic image leaves out a huge (and slightly less appetizing) source of nourishment: dead stuff. John C. Moore details the "brown food chain," explaining how such unlikely delicacies as pond scum and animal poop contribute enormous amounts of energy to our ecosystems.

As students watch the video, they answer the following questions:

1.  What percentage, on average, of living plant biomass on land is consumed alive by herbivores?

a.  More than 75%

b.  50%

c. 25%

d. Less than 10%

2.  Which of the following terms refer to an organism that consumes non-living organic material?

a.  Herbivore

b.  Predator

c.  Detritivore

d.  Mutualist 

3.  Detritus is defined as ___________.

a.  Dead plant biomass

b.  Feces and waste from animal metabolism

c.  Dead animal biomass

d.  All of the above

4.  What molecule from the atmosphere is captured during photosynthesis to generate plant food and biomass?

a.  CH4

b.  CO2

c.  H20

d. C6H1206

Explore

25 minutes

In this section of the lesson, students explore food chains by completing a module on Competition from the Concord Consortium.

Module Description

Explore a NetLogo model of populations of rabbits, grass, and weeds. First, adjust the model to start with a different rabbit population size. Then adjust model variables, such as how fast the plants or weeds grow, to get more grass than weeds. Change the amount of energy the grass or weeds provide to the rabbits and the food preference. Use line graphs to monitor the effects of changes you make to the model, and determine which settings affect the proportion of grass to weeds when rabbits eat both.(SP2 - Developing and Using Models)

Procedure:

  • Students complete activity in pairs
  • Students are required to discuss module questions as they complete exercises

Teacher Note:  Concord Consortium requires an updated version of flash software and CC Launcher. 

Explain

15 minutes

In this section of the lesson, students read an article titled Energy Pyramids from cK-12.  

Once students have read article they answer text-dependent questions (RST.6-8.1:Cite specific textual evidence to support analysis of science and technical texts.)

  1. When an herbivore eats a plant, what happens to 90% of the energy obtained from that plant?
  2. What is a trophic level?
  3. Why are the number of trophic levels limited?
  4. In a forest community, caterpillars eat leaves, and bird eat caterpillars. Draw an energy pyramid using this information.

In addition to the reading, I show students the Ecological Pyramids video. This video meets the needs of EL and visual learners.

As students watch the video, they answer the following questions in their interactive notebooks:

  1. What are three types of ecological pyramids? How do their shapes compare?
  2. Do you think it would be possible to construct a pyramid where the number of carnivores was more than the number of herbivores? Why or why not?
  3. Do you think it would be possible to construct a pyramid where the biomass of carnivores was more than the biomass of herbivores? How does this compare to a numbers pyramid.
  4. What consumes energy at each trophic level? How does this contribute to energy loss between trophic levels?

Elaborate

10 minutes

In this section of lesson students elaborate on what they have learned by reading an article titled The Eco Pyramid from ReadWorks.

The non-profit ReadWorks is committed to solving the nation's reading comprehension crisis by giving teachers the research-proven tools and support they need to improve the academic achievement of their students.

ReadWorks provides research-based units, lessons, and authentic, leveled non-fiction and literary passages directly to educators online, for free, to be shared broadly.

The ReadWorks curriculum is aligned to the Common Core State Standards and the standards of all 50 states. Most importantly, ReadWorks is faithful to the most effective research-proven instructional practices in reading comprehension.

At end of reading students answer text-dependent questions included in reading passage.

Students use the Marking the Text strategy to interact with text.

Evaluate

5 minutes

In this section of the lesson students develop a visual model  (i.e. drawing, comic strip, graph) that describes the cycling of energy in an energy pyramid. (MS-LS2-3. Develop a model to describe the cycling of matter and flow of energy among living and nonliving parts of an ecosystem./CCC - Energy and Matter -The transfer of energy can be tracked as energy flows through a natural system.)  

Students are required to use the following vocabulary:

1. Producer

2. Primary Consumer

3. Secondary Consumer

4. Tertiary Consumer 

In addition to vocabulary terms above students are required to write down examples of each in their model, for example deer as primary consumer.