Unit

NY Harbor Populations Investigation

Grade

6-8th

Class Periods

2

Setting

Classroom

Subject Areas

Science


Summary

Students will each play the role of an estuary organism and together the class will create an estuarine food web with string connecting the organisms to each other.

Objectives

  • Identify at least two organisms found in New York Harbor.

  • Understand that organisms within an ecosystem are dependent on each other.

  • Articulate the energy transfer from one organism to the next.

Materials and Resources

Supplies

  • Food Web Cards

  • String or yarn

  • Clipboards (Ideally, one for every students plus one for every pair.  If you have 30 students you need 45 clipboards.)

  • Basic classroom supplies like markers, stickers, construction paper

  • Scissors

Before you get started

Tips for Teachers

  • You will have more success with this activity if you take the time to read through all the Food Web Cards, familiarize yourself with them and decide if you want to use them all.  
  • Consider printing more than one card for species that are abundant, such as diatoms, dinoflagellates, and amphipods.
  • Each student should have ONE Food Web Card.
  • Use the phrasing “x gets energy from y” instead of “x eats y” in order to emphasize that one important aspect of a food web is the fact that is depicts the energy flow in an ecosystem. 

Teachers might want to consult these additional resources for more background:

Preparation

  • Food Web Cards should be printed with the photograph on one side of the card and the information on the other side of the card.

  • All cards should be laminated, hole punched and strung, so they hang around a student’s neck.  This allows the students to be hands-free during the activity.

  • Decide beforehand how you will assign each student their card.  Randomly?  Based on students’ prior questions or interest?

Background

The food chain begins with producers, organisms such as green plants, that can make their own food. Through photosynthesis, producers convert solar energy to chemical energy. Out of all the energy a plant receives from the sun, only about three percent is converted into chemical energy.

Plants are eaten by consumers, which are organisms that cannot make their own food. Herbivores are consumers that eat only producers. Consumers that prey on other consumers are called carnivores. If an animal can get its energy by ingesting both producers and consumers, it is an omnivore.


A food chain does not consist of a set amount of energy that is passed along like a baton from one organism to another. In reality, the ‘baton’ gets smaller and smaller with each transfer. When an herbivore eats a plant, it does not get all the energy that the plant captured from the sun. This decrease is only partly due to the fact that the herbivore may not eat all parts of the plant, or it may not be able to digest all of what it does eat. These undigested plant parts are excreted as waste.


The main reason that much of the energy obtained by one organism isn't passed on in the food chain is because it is no longer available. Some energy has already been used by the first organism. A plant uses some of the energy it receives to grow and function. A herbivore uses its energy to grow, but also to look for food and run away from predators. A predator uses large amounts of energy to chase after its food in addition to its regular life processes (e.g., breathing, digesting food, moving). The energy these organisms use leaves their bodies -- and eventually the Earth -- in the form of heat.


Instruction Plan

Engage

  1. If you have taken your students on an expedition to your Oyster Restoration Station (ORS), begin with the following line of questions:

    • What organisms did you see at your ORS?  

    • Where on the ORS did you observe them?  Were they attached to something?  Crawling on something?

    • What do you think this organism gets energy from?  

    • What do you think gets energy from this organism?


  2. Each student gets one Food Web Card.  All students will have an organism on their cards, except for “detritus” and “the sun.”


  3. Give the students time to familiarize themselves with the information on their card.


  4. Consider providing additional time and resources (found under Teacher Resources) for the students to read more detail about their organism, especially if you hear a lot of great questions.


  5. Ask the students to present their card to a partner or small group, in order to reinforce what they have learned about their organism.  

Explore

  1. Once the students are familiar with their card, it is time to get in a circle.


  2. You will need enough space to get your whole class standing in a circle, with nothing in the middle of the circle.  You could move desks out of the way in the classroom, go outdoors, or go into a gymnasium.  


  3. Make sure each student has the card around his/her neck.


  4. Stand in the middle of the circle and explain: You are going to create your own food web.  The string represents energy transfer between organisms.  


  5. Ask: In this food web, where does the energy originate? (Note: There are some food webs where the source of energy is hydrothermal vents on the seafloor.)


  6. Give the Sun the end of the string.


  7. Ask all the students to glance at their card to figure out who gets energy from the sun.


  8. Based on the responses, connect the string to an organism.


  9. Then ask who gets energy from that organism.


  10. Continue until the string has gone all the way up the food chain to a top consumer.


  11. Ask: Do you think any organisms get their energy by consuming this animal?  Give students time to think about and discuss different aspects of the question.


  12. Discuss decomposers (e.g. bacteria) in more detail.  Allow students to ask questions.


  13. Explain: sometimes decomposers don't act that quickly, and dead organic matter remains for a time in larger bits like detritus.


  14. Explain: the difference between the cycling of matter and the flow of energy through an ecosystem. Bacteria and detritus die, and the matter that makes up their bodies does return to the ecosystem, through soil, air, and water.  But the energy that was originally captured from the Sun by a primary producer is now in the process of being converted to heat.  It will leave the Earth as radiation, the same way it arrived on Earth as radiation from the Sun.  


  15. The string represents energy transfer, so there should come a point where you cut the string and start again.   


  16. Use a new piece of string to start again at the Sun.


  17. When the string comes to someone who is already holding a piece of string, use the second piece of string to tie a simple overhand knot to connect it to the first piece of string.


  1. Continue this process until at everyone in the class is holding at least one piece of string (it’s okay if some students get reconnected to the web multiple times, and some are only connected once).

Explain

  1. Remind the students that the food web shows the energy transfer through the ecosystem.


  2. Consider asking the following types of questions:

    • In this food web, where does the energy originate? (The sun)
    • How do the other organisms in this food web obtain energy? (Consuming each other)
    • Once an organism has energy where does it go and what is it used for? (used for growth and other life processes, and eventually converted to heat energy that leaves the Earth as radiation)
  3. Consider introducing vocabulary such as primary producer, omnivore and consumer.


  4. Hand out a clipboard and Food Web Questions to each student.


  5. Ask students to secure their string in the clip of the clipboard.  


  6. While students are standing in the circle, they look at the strings and connections and complete the Food Web Questions.

Elaborate

  1. The energy transfer in this food web is represented by the string.  What could we add to our model that would show the energy loss from one organism to the next?


  2. Show the class the basic classroom supplies like markers, construction paper and stickers to prompt some creative thinking.  


  3. The students put their clipboards down at their feet together, thereby putting the entire food web down on the ground in order to illustrate the energy loss in the food web.


  4. Next, tell the students to take the string off their clipboards, pinch the string tightly between their fingers and leave their clipboards down at their feet.


  5. Tug on a piece of the string at one point in the web and then another point.  You can do this several times.


  6. Ask: Which students can feel the tug in other parts of the web?


  7. Ask: Why is it that if you tug on the string at one point, students can feel it at another point – even if they aren’t directly connected to the string you are tugging?


  8. Have all the students take one small step back, pulling on their string with a little pressure, without letting go.


  9. Ask: What would happen if one of these organisms was eliminated from the ecosystem?  What would happen to the web?  


  10. Choose an organism that has more than one string leading to it (e.g. an amphipod) and cut all the strings leading to it. 


    11. Discuss what happens to the food web and the difference in the way food web “feels” (since the students were pulling on the web with some pressure and when those strings were cut.)

Evaluate

  1. Students secure their string to the clip of the clipboard at their feet.


  2. Students take off their Food Web Card and put it on top of the clipboard.  


  3. Students get into pairs and get a new clipboard.


  4. Pairs sketch out the food web on the back of their Food Web Questions handout.  


  5. As they sketch, pairs should discuss if they think any modifications need to be made to the food web.  They can note these changes in their sketch.

Extend

  1. The students look back at the food chain they chose in their Food Web Questions and decide if they would still like to focus on this food chain.


  2. This food chain has already been represented with string.  


  3. Ask: How could we represent this food chain a different way.  Possibilities include: an essay, cartoon, pie chart, powerpoint, etc.

Standards

NGSS - Cross-Cutting Concepts

  • Cause and Effect

    • Cause and effect relationships may be used to predict phenomena in natural or designed systems.
    • Phenomena may have more than one cause, and some cause and effect relationships in systems can only be described using probability.
    • Cause and effect relationships may be used to predict phenomena in natural systems.
    • Relationships can be classified as causal or correlational, and correlation does not necessarily imply causation.
  • Energy and Matter

    • The transfer of energy can be tracked as energy flows through a designed or natural system
    • The transfer of energy can be tracked as energy flows through a natural system.
  • Influence of Engineering, Technology, and Science on Society and the Natural World

    • All human activity draws on natural resources and has both short and long-term consequences, positive as well as negative, for the health of people and the natural environment.
  • Patterns

    • Graphs and charts can be used to identify patterns in data.
    • Graphs, charts, and images can be used to identify patterns in data.
  • Stability and Change

    • Stability might be disturbed either by sudden events or gradual changes that accumulate over time.
  • Systems and System Models

    • Models can be used to represent systems and their interactions.
    • Models can be used to represent systems and their interactions—such as inputs, processes and outputs—and energy and matter flows within systems.

NGSS - Disciplinary Core Ideas

  • LS1.A: Structure and Function

    • Within cells, special structures are responsible for particular functions, and the cell membrane forms the boundary that controls what enters and leaves the cell.
  • LS2.A: Interdependent Relationships in Ecosystems

    • Growth of organisms and population increases are limited by access to resources.
    • Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors.
  • LS2.B: Cycle of Matter and Energy Transfer in Ecosystems

    • Food webs are models that demonstrate how matter and energy is transferred between producers, consumers, and decomposers as the three groups interact within an ecosystem. Transfers of matter into and out of the physical environment occur at every level. Decomposers recycle nutrients from dead plant or animal matter back to the soil in terrestrial environments or to the water in aquatic environments. The atoms that make up the organisms in an ecosystem are cycled repeatedly between the living and nonliving parts of the ecosystem.
  • LS2.C: Ecosystem Dynamics, Functioning, and Resilience

    • Ecosystems are dynamic in nature; their characteristics can vary over time. Disruptions to any physical or biological component of an ecosystem can lead to shifts in all its populations.

NGSS - Science and Engineering Practices

  • Analyzing and Interpreting Data

    • Analyze and interpret data to provide evidence for phenomena.
  • Constructing Explanations and Designing Solutions

    • Construct an explanation that includes qualitative or quantitative relationships between variables that predict phenomena.
  • Engaging in Argument from Evidence

    • Construct and present oral and written arguments supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.

NYC Science Scope & Sequence - Units

  • Grade 6, Unit 4

    • Interdependence