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Flow of Energy through Trophic Levels

Lesson Plan

Flow of Energy through Trophic Levels

  • Grade Levels
    8th Grade
  • Related Academic Standards
    3.3.8.A5

    Explain how the curvature of the earth contributes to climate.

    Compare and contrast water vapor, clouds, and humidity.
    3.3.8.A6

    CHANGES

    Explain changes in earth systems in terms of energy transformation and transport.

    MODELS

    Explain how satellite images, models, and maps are used to identify Earth’s resources.
    3.3.8.A7
    • Compare and contrast scientific theories.
    • Know that both direct and indirect observations are used by scientists to study the natural world and universe.
    • Identify questions and concepts that guide scientific investigations.
    • Formulate and revise explanations and models using logic and evidence.
    • Recognize and analyze alternative explanations and models.
    • Explain the importance of accuracy and precision in making valid measurements.
    3.1.8.A8

    CHANGE AND CONSTANCY

    Explain mechanisms organisms use to adapt to their environment.
    3.1.8.A9
    • Compare and contrast scientific theories.
    • Know that both direct and indirect observations are used by scientists to study the natural world and universe.
    • Identify questions and concepts that guide scientific investigations.
    • Formulate and revise explanations and models using logic and evidence.
    • Recognize and analyze alternative explanations and models.
    • Explain the importance of accuracy and precision in making valid measurements.
    3.3.8.A1

    Distinguish between physical and chemical weathering.

    Compare and contrast the types of energy that drive Earth’s systems.
    3.3.8.A2
    Describe renewable and nonrenewable energy resources.
    3.3.8.A3
    Explain how matter on earth is conserved throughout the geological processes over time.
    3.3.8.A4
    Explain how the oceans form one interconnected circulation system powered by wind, tides, the Earth’s rotation, and water density differences.
  • Assessment Anchors
    S8.A.3

    Systems, Models, and Patterns
    S8.B.3

    Ecological Behavior and Systems
  • Eligible Content
    S8.A.3.1.1
    Describe a system (e.g., watershed, circulatory system, heating system, agricultural system) as a group of related parts with specific roles that work together to achieve an observed result.
    S8.A.3.1.2
    Explain the concept of order in a system [e.g., (first to last: manufacturing steps, trophic levels); (simple to complex: cell, tissue, organ, organ system)].
    S8.A.3.1.5
    Explain how components of natural and human-made systems play different roles in a working system.
    S8.A.3.2.1
    Describe how scientists use models to explore relationships in natural systems (e.g., an ecosystem, river system, the solar system).
    S8.B.3.1.1
    Explain the flow of energy through an ecosystem (e.g., food chains, food webs).
    S8.B.3.1.3
    Explain relationships among organisms (e.g., producers/consumers, predator/prey) in an ecosystem.
  • Big Ideas
    • A technological world requires that humans develop capabilities to solve technological challenges and improve products for the way we live.
    • An object’s motion is the result of all forces acting on it.
    • Each area of technology has a set of characteristics that separates it from others; however, many areas overlap in order to meet human needs and wants.
    • Energy is neither created nor destroyed. Energy can be transformed from one form to another, but transformation between forms often results in the loss of useable energy through the production of heat.
    • Matter has observable physical properties and the potential to mix and form new materials.
    • Solid, liquid and gaseous earth materials all circulate in large scale systems at a variety of time scales, giving rise to landscapes, the rock cycle, ocean currents, weather, and climate.
    • Technological design is a creative process that anyone can do which may result in new inventions and innovations.
    • Technological literacy is the ability to use, assess and manage technology around us.
    • Technology is created, used and modified by humans.
    • The cell is the basic unit of structure and function for all living things.
  • Concepts
    • A substance has characteristic properties such as density, boiling point, freezing point, solubility, all of which are independent of the mass or volume of the sample.
    • A technological design & problem solving process changes ideas into a final product or system.
    • All living things are made up of smaller units called cells.
    • All matter is made up of building blocks called atoms. Atoms are characterized by their parts including protons, electrons, and neutrons.
    • All matter is made up of particles, which are far too small to see directly through a microscope.
    • All multicellular organisms have systems that interact with one another to perform specific functions and enable the organism to function as a whole.
    • An object will stay at rest or continue at a constant velocity unless acted upon by an external, unbalanced force.
    • Batteries store chemical energy and transform it into electrical energy.
    • Bio-related technologies are the processes of using biological mater to make or modify products.
    • Bio-related technologies are the processes of using biological organisms to make or modify products.
    • Cells carry out the many functions needed to sustain life.
    • Cells grow and divide thereby producing more cells.
    • Cells take in nutrients that they use to provide energy to carry out their life functions.
    • Changing a substance’s state of matter may change its density but not its composition.
    • Communication is the process of composing, sending, and receiving messages through technology.
    • Communication is the process of composing, sending, and receiving messages using technological devices.
    • Compounds may only be broken down into simpler types of matter (elements) by chemical means.
    • Construction is the process of turning materials into useful structures.
    • Construction is the process of turning raw materials into useful structures.
    • Creating optimal solutions under constraints are a primary component of technological problem solving (e.g., tools/machines, materials, information, people, capital, energy, and time).
    • Decisions about the use of products and systems can result in expected and unexpected consequences.
    • Decisions about the use of products and systems can result in known and unexpected consequences.
    • Different body tissues and organs are made up of different kinds of cells.
    • Disease affects the structures and/or functions of an organism.
    • Earth materials (rocks and soils) can be classified by their composition and texture and those features can be interpreted to infer the history of the material.
    • Elements are the basic building blocks of matter that cannot be broken down chemically and are made up all of the same type of atoms.
    • Energy and power technologies are the processes of converting energy sources into useful power.
    • Energy and power technologies use processes to convert energy into power.
    • Energy appears in different forms and can be transformed within a system.
    • Energy can be transformed within a system or transferred from one system to another (or from a system to its environment) in different ways. Thermal energy is transferred from warmer objects to cooler objects. Mechanical energy can be transferred when two objects push or pull on one another. Electromagnetic energy can be transferred when an electrical source such as a battery or generator is connected in a complete circuit to an electrical device. Chemical energy is transferred when particles are rearranged in a chemical reaction.
    • Energy from the sun warms air and water, which creates moving currents within them. This movement causes changes on the earth’s surface.
    • Every organism has a set of genetic instructions that determines its inherited traits.
    • Everything on or near the earth is pulled toward Earth’s center by a gravitational force. Celestial revolutions are caused by gravitational attraction.
    • Friction is an example of an electromagnetic force that opposes motion between two surfaces.
    • Heat energy is usually a by-product of an energy transformation.
    • Heat flow from the earth and motion within the earth lead the outer shell of the earth to move around in large rigid pieces (plates) and leads to the creation and destruction of ocean basins, motion of continents relative to one another, earthquakes, volcanic eruptions, and development of mountain belts.
    • Heat moves in predictable ways, normally flowing from warmer objects to cooler ones, until the objects reach the same temperature.
    • Human activities change land cover and land use patterns, add or remove nutrients from ecosystems and modify some of the fundamental cycles of the earth system, including the carbon cycle. These changes can have unexpected and far-reaching effects due to the complex interconnections among earth systems.
    • Human decision making (e.g. Human needs and wants plus cultural considerations) drives the selection and/or use of technologies.
    • In a technological world, inventions and innovations must be carefully assessed by individuals and society as a whole.
    • Innovation is the process of improving an existing product, process, or system.
    • Innovation is the process of modifying an existing product, process, or system to improve it.
    • Interaction of circulating air masses gives rise to a wide variety of weather phenomena including fronts, mid-latitude cyclones (and anti-cyclones), and severe weather (tropical storms, tornados, severe thunderstorms, etc.).
    • Invention is a process of creating new products, processes, or systems.
    • Invention is a process of turning ideas and imagination into new products, processes, or systems.
    • Inventions and innovations must be carefully assessed by individuals and society.
    • Large scale wind patterns drive surface currents in the oceans and affects weather.
    • Manufacturing is the process of turning materials into useful products.
    • Manufacturing is the process of turning raw materials into useful products.
    • Mass is a measure of the amount of matter in an object.
    • Materials are characterized by having a specific amount of mass in each unit of volume (density).
    • Mechanical advantage, using less force over a greater distance, allows the same work to be performed with less effort.
    • Models (graphs) of an object’s velocity versus time can be used to infer the presence of absence of unbalanced forces.
    • Moving electric charges produce magnetic forces and moving magnets produce electric forces.
    • Particles are always in motion with the smallest motion in solids progressing to the largest motion in gases.
    • People select, create, and use technology.
    • Plants transform light energy into chemical energy, which then can be used by other living things.
    • Safety is a preeminent concern for all technological development and use.
    • Safety is one of the most important concerns for all technological development and use.
    • Science and technology are interconnected.
    • Science is the study of the natural world and technology is the study of the human designed world but both are inextricably connected.
    • Simple machines help accomplish a task with less effort by either changing the direction of motion or increasing the mechanical advantage.
    • Some changes in Earth’s surface are abrupt, such as earthquakes, volcanoes, meteor impacts, and landslides. Others are gradual, such as the lifting up of mountains or their wearing away by erosion.
    • Some organisms are made up of only one cell.
    • Specialized cells perform specialized functions in multicellular organisms.
    • Technological design & problem solving follows many steps.
    • Technological design & problem solving includes both formative and summative analysis.
    • Technological design & problem solving includes clearly communicated solutions.
    • Technological design & problem solving includes frequent checking.
    • Technological design & problem solving requires hands-on applications.
    • Technological design & problem solving requires the ability to clearly communicate engineered solutions.
    • Technological design & problem solving requires the application of hands-on abilities such as sketching, prototyping, and fabricating.
    • Technological design & problem solving transforms an idea into a final product or system.
    • Technological design & problem solving utilizes a series of steps that take place in a well-defined sequence.
    • Technological literacy is necessary for a productive workforce.
    • Technological literacy is necessary for all citizens.
    • Technological literacy is the ability to understand, use, assess, design, and create technology.
    • Technological literacy requires lifelong learning.
    • Technology and society impact each other.
    • The abilities required in a technological world include diagnosing, troubleshooting, analyzing and maintaining systems.
    • The abilities required in a technological world include understanding, fixing, and maintaining systems.
    • The atmosphere circulates in large scale patterns which steer weather systems due to heat from the sun.
    • The circulation of the ocean and atmosphere carries heat energy and has a strong influence on climate around the world.
    • The cycling of water in and out of the atmosphere plays an important role in determining climatic patterns.
    • The Earth is mostly rock, with a metallic core, a thin layer of water covering about ¾ of the surface and surrounded by a thin blanket of air.
    • The Earth’s revolution around the Sun causes the seasons and the year. Because of the Earth’s tilted axis, sunlight falls more intensely on different parts of the earth during different parts of the year, producing the seasons and seasonal patterns in weather.
    • The Earth’s rotation around its tilted axis causes day and night.
    • The gene is the basic unit of inheritance.
    • The goal of technology is to meet human needs and wants.
    • The gravitational force is a universal force that depends on how much mass the objects have and how far apart they are.
    • The magnitude of the gravitational force is weight (oz, lb, newtons).
    • The Moon’s revolution around the earth once in about 28 days changes what part of the moon is lighted by the sun and how much of that part we can see from the earth, giving rise to lunar phases.
    • The rhythms of the Earth are caused by 3 celestial motions: The Earth’s rotation, revolution around the sun, and the Moons’ revolution around the Earth.
    • The study of the impacts of technological systems enables us to plan and direct technological developments.
    • The sun is the main source of energy for biological systems on the surface of the earth.
    • The use of technology involves weighing the trade-offs of the positive and negative effects.
    • There are defining structures of cells for both plants and animals.
    • There are over one hundred known elements each with characteristic properties from which all other matter is made.
    • There are structural and functional similarities and differences that characterize diverse living things.
    • There is a relationship between structure and function at all biological levels of organization.
    • Thousands of layers of sedimentary rock confirm the long history of the changing surface of the earth and the changing life forms whose remains are found in successive layers.
    • Transportation is the process of safely and efficiently moving people and products.
    • Two of the fundamental forces that exist in the universe are gravity and electromagnetism.
    • Unbalanced forces acting on an object cause changes in its velocity.
    • Understanding technological systems help us plan and control technological developments.
    • When two or more substances are combined, they may form a mixture and maintain their original properties or they may react chemically to form a new substance with new properties.
    • While science is the study of the natural world, technology is the study of the human designed world.
  • Competencies
    • Clearly communicate technological solutions.
    • Demonstrate how technological progress promotes the advancement of science, technology, engineering and mathematics (STEM).
    • Describe how science and technology work together.
    • Describe how technology impacts society.
    • Describe the complementary roles of scientific knowledge and technological application.
    • Describe the flow of energy from the sun, throughout the earth system, living and non-living, from the cellular scale to the global scale, and describe the transformations of that energy as it moves through the system.
    • Describe the nature of technology and the consequences of technological activity which impact society and the world.
    • Describe the nature of technology.
    • Describe the relationships among the parts of a system, the ways that they work together, the flow of matter or energy through the system, and the feedback and control mechanism present in the system.
    • Design and develop the ability to create and send messages using technological devices.
    • Design and develop the ability to safely and effectively use tools and materials to build structures.
    • Design and develop the ability to safely and effectively use tools and materials to convert energy into power.
    • Design and develop the ability to safely and effectively use tools and materials to create bio-related products and systems using technology.
    • Design and develop the ability to safely and effectively use tools and materials to create vehicles that transport people and products.
    • Design and develop the ability to safely and effectively use tools and materials to manufacture products.
    • Develop the abilities to use and maintain technological products and systems.
    • Differentiate between the study of science and technology.
    • Explain how making informed decisions about the development and use of technology may have known and unexpected consequences.
    • Explain how people select, create and use technology.
    • Explain how technology has and can change the human condition throughout time.
    • Explain how technology has and can change the world.
    • Explain the importance of carefully assessing technological inventions and innovations.
    • Recognize the importance of using technological knowledge in society.
    • Use design and problem solving skills to solve technological challenges.
    • Use models and patterns to make predictions, draw inferences, or explain scientific and technological concepts.
    • Verify that engineering design is influenced by personal characteristics, such as creativity, resourcefulness and the ability to visualize and think abstractly.

Objectives

In this lesson, students identify the roles of organisms in food chains and create food chains. Students will:

  • describe the trophic levels in a food chain and a food web.
  • identify the roles of various organisms in an ecosystem.
  • construct an energy pyramid model and describe the flow of energy through an ecosystem.

Essential Questions

Vocabulary

  • Ecology: The study of how organisms interact with their environment and with other organisms.
  • Ecosystem: All of the organisms that live in a certain area and their nonliving environment.
  • Food Chain: Steps in an ecosystem that show the transfer of energy as organisms are consuming one another.
  • Food Web: A complex network of interactions that shows the feeding relationships between organisms in an ecosystem.
  • Energy Pyramid: A diagram showing the flow of energy through a food chain.
  • Trophic Levels: The feeding levels in a food chain.
  • Producers: Organisms that use inorganic material such as sunlight or chemical compounds to produce their own food.
  • Consumers: Organisms that eat other organisms for energy.
  • Primary Consumers (herbivores): Organisms that eat producers.
  • Carnivores: Organisms that eat meat.
  • Secondary Consumers: Carnivores that eat herbivores.
  • Tertiary Consumers: Carnivores that eat secondary consumers.
  • Omnivores: Organisms that eat both plants and meat.
  • Decomposers: Organisms (bacteria and fungi) that break down decaying matter for energy and nutrients.
  • Law of Conservation of Energy: States that energy cannot be created or destroyed; it can only be transformed.
  • Ten Percent Rule: Only about 10 percent of the energy available in one trophic level is available to organisms in the next higher trophic level.

Duration

90 minutes/2 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.

Materials

Related Unit and Lesson Plans

Related Materials & Resources

The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.

  • Food Chains & Food Webs

www.vtaide.com/png/foodchains.htm

  • Energy Pyramid interactive tutorial; forest, prairie, and ocean energy pyramid examples

www.harcourtschool.com/activity/science_up_close/314/deploy/interface.html

  • Pond Food Web interactive activity

www.harcourtschool.com/activity/food/pond_activity.html

  • A Food Pyramid in the Hot Desert Biome (shows kilocalories at each trophic level)

www.world-builders.org/lessons/less/biomes/desert/hot-despy.html

  • A Deciduous Forest Energy Pyramid (shows kilocalories at each trophic level)

www.world-builders.org/lessons/less/biomes/deciduous/decpy.html

Formative Assessment

  • View
    • While students work on the food web individually, monitor the classroom and ask questions to check for understanding of the concepts of trophic levels and direction of the flow of energy.
    • Collect the Energy Pyramid and handout from the Energy Pyramid Activity for individual assessment.

Suggested Instructional Supports

  • View
    Scaffolding, Active Engagement, Modeling, Explicit Instruction
    W: This lesson focuses on the flow of energy through ecosystems. Students will examine trophic levels using three different models: food chains, food webs, and energy pyramids. Students are evaluated on their ability to create each of the three models and their understanding of related vocabulary terms.
    H: Students are hooked into the lesson with a kinesthetic activity, in which the class guides student volunteers in creating a food chain.
    E: This lesson begins with a whole-class demonstration and instruction. Then it moves to a small-group hands-on activity, and students answer follow-up questions to the activity individually.
    R: The follow-up questions in the Energy Pyramid Activity ask students to reflect on how energy flows through ecosystems.
    E: Students are evaluated based on their creation of a food web and their work on the Energy Pyramid Activity.
    T: Students may benefit from extra practice with the vocabulary from this lesson, which will also be used in Lessons 2 and 3. An extension for students who may be going beyond the standards is provided as well.
    O: This lesson begins with construction of a food chain and builds on the vocabulary and concepts from that activity throughout the rest of the lesson.

Instructional Procedures

  • View

    Part 1

    Perform a short demonstration of a food chain. Call on seven student volunteers, and have them stand at the front of the classroom. Designate four of them as “squirrel,” “mountain lion,” “acorn,” and “fox.” Give a sheet of paper with an arrow to each of the other three students. Tell them they will represent energy flow. Have the class arrange the first four students side-by-side, in order of “who eats whom” from left to right. Then, have the class arrange the three students with arrows, so that the arrows point in the direction of energy flow because of the feeding relationships shown. The correct order is:

    acorn → squirrel → fox → mountain lion

    Have students copy the food chain into their notes. Define trophic levels. Then guide students in labeling the acorn as a producer, the squirrel as a primary consumer, the fox as a secondary consumer, and the mountain lion as a tertiary consumer. Explain the flow of energy between each of the trophic levels. Also, define the terms herbivore, carnivore and omnivore, and have students identify an example of each on the food chain. (The herbivore is the squirrel, the carnivore is the mountain lion, and the omnivore is the fox.) Also explain the role of decomposers, which are mostly bacteria and fungi. These organisms recycle nutrients from decaying organic material. Be sure to explain that decomposers can be placed at any point in a food web.

    Ask the class to name more organisms that could belong to the forest ecosystem from the food chain. Begin creating a food web, writing each new organism on the board or overhead projector, and using arrows between the organisms to show the flow of energy.

    Individual: After demonstrating how to place a few organisms into the food web, students continue creating the food web in their notes individually.

    Part 2

    Tell students ecologists use many different models to study the flow of energy through ecosystems. Food chains and food webs both show the direction of energy flow, but “energy pyramids” can show the direction and the amount of energy flow between trophic levels. Show them an energy pyramid like the one below (S-8-9-1_Marine Energy Pyramid.docx):

     

    l1-01pyramid.png

    Source: www.sciencelearn.org.nz/Contexts/Life-in-the-Sea/Science-Ideas-and-Concepts/Marine-food-webs

     

    Explain the ten percent rule, the concept that only about 10 percent of the energy available in one trophic level is available to organisms in the next trophic level. Explain that some of the energy in each level is used for life processes and some energy is given off as heat. Ask students,

    • “If 100 percent of energy is stored in the producers in the food chain, what percent is available to primary consumers?” (10 percent)
    • “What percent is available to the secondary consumers?” (1 percent)
    • “What percent is available to the tertiary consumers?” (0.1 percent)

    Tell students that energy available at each trophic level is measured in units called kilocalories (kcal). Explain that if 7,000 kcal are available in producers, then only 700 kcal can be transferred to primary consumers. Have students calculate the kcal available for secondary consumers and tertiary consumers.

    In small groups, have students complete the Energy Pyramid Activity (S-8-9-1_Energy Pyramid Activity-Student Version.doc and S-8-9-1_Energy Pyramid Activity-Teacher Version.doc). Have each student answer the questions to the Energy Pyramid Activity individually.

    Extension:

    • Students who might need an opportunity for additional learning can arrange a list of names of other organisms in the food web from a list that you provide (e.g., deer, sparrow, owl, wolf, bear, mouse, skunk, insects, fish). Also, before the lesson begins, provide a list of the vocabulary terms and definitions. Students may reinforce learning by practice creating a food web with the Pond Food Web interactive activity or watching the Energy Pyramid tutorial (see Related Resources).
    • Students who may be going beyond the standards can create a food web with specific organisms that live in the local Pennsylvania ecosystem.
    • Students who may be going above the standards can write a short essay on the impact of an ecosystem’s food web if one organism becomes extinct or loses its habitat within the ecosystem. The essay should touch on how other organisms in the food web could be impacted by the event.

Related Instructional Videos

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DRAFT 05/16/2011
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