Day 2-Food Webs...Moving Matter in an Ecosystem

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SWBAT define food web and explain how a food web can change if a certain organism is removed.

Big Idea

Students will build a food web diagram and illustrate the movement of matter through a series of food chains.

Lesson Overview

5e Lesson Plan Model

Many of my science lessons are based upon and taught using the 5E lesson plan model: Engage, Explore, Explain, Elaborate, and Evaluate. This lesson plan model allows me to incorporate a variety of learning opportunities and strategies for students.  With multiple learning experiences, students can gain new ideas, demonstrate thinking, draw conclusions, develop critical thinking skills, and interact with peers through discussions and hands-on activities.  With each stage in this lesson model, I select strategies that will serve students best for the concepts and content being delivered to them.  These strategies were selected for this lesson to facilitate peer discussions, participation in a group activity, reflective learning practices, and accountability for learning.

Unit Focus  

The Ecosystems and Interactions unit focuses on students recognizing the interrelationship between organisms and their ecosystems.  It engages students in understanding that organisms have observable characteristics that are fully inherited and can be affected by the climate and/or environment. Students distinguish structures that define classes of animals and plants, and develop an understanding that all organisms go through predictable life cycles. They learn that organisms depend upon one another for growth and development and discover that plants use the sun's energy to produce food for themselves. They observe how the sun's energy is transferred within a food chain from producers to consumers to decomposers. 

Lesson Synopsis    

In this lesson, Day 2-Food Webs...Moving Matter in an Ecosystem, students learn how many food chains can create a food web. The lesson begins by using their food chain diagrams from yesterday to review on food chains. Then, they work as a group to develop a food web using each members good chain. Once food webs are complete, we engage in a discussion as we analyze the web. I wrap up the lesson by having them think about what would happen if one organism was removed from their food web. I want them to recognize that if an organism did not exist, that their diagram would change completely.

Next Generation Science Standards  

This lesson will address and support future lessons on the following NGSS Standard(s): 

5-LS2-1. Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment

5-PS3-1. Use models to describe that energy in animals’ food (used for body repair, growth, motion, and to maintain body warmth) was once energy from the sun.  

Scientific & Engineering Practices

Students are engaged in the following scientific and engineering practices:

2.) Developing and Using Models- Students create a diagram of a food web. Their web is used to illustrate the flow of energy through an ecosystem. They use arrows to show this movement.

4.) Analyze and Interpret Data- Students analyze a food web and determine what would happen if an organism was removed from it. How would the web change? They construct an explanation about it.

Crosscutting Concepts

The Day 2-Food Webs...Moving Matter in an Ecosystem lesson will correlate to other interdisciplinary areas.  These Crosscutting Concepts include:

4.) Systems and System Models: Students create a model to represent flow of relationships between organisms in an ecosystem.

5.) Energy and Matter: Student develop a food web diagram to illustrate the movement of energy from one organism to another using the sun as the primary source of energy.

Disciplinary Core Ideas

Disciplinary Core Ideas within this lesson include:

LS1.C Organization for mater and energy flow in organisms.

LS2.A Interdependent Relationships in Ecosystems


Importance of Modeling to Develop Student

Responsibility, Accountability, and Independence 

Depending upon the time of year, this lesson is taught, teachers should consider modeling how groups should work together; establish group norms for activities, class discussions, and partner talks.  In addition, it is important to model think aloud strategies.  This sets up students to be more expressive and develop thinking skills during an activity.  The first half of the year, I model what group work and/or talks “look like and sound like.”  I intervene the moment students are off task with reminders and redirecting.  By the second and last half of the year, I am able to ask students, “Who can give of three reminders for group activities to be successful?” Who can tell us two reminders for partner talks?”  Students take responsibility for becoming successful learners.  Again before teaching this lesson, consider the time of year, it may be necessary to do a lot of front loading to get students to eventually become more independent and transition through the lessons in a timely manner.


15 minutes

Reviewing a Food Chain

I begin asking students to take out their food chain diagram from yesterday.  I tell them to look it over (analyze it) for a few minutes.  Then I direct students to locate and point to the producer in their food chain.  I ask, "Who has berries as their producer?" With several hands raised, I draw the berries on the board. Then, I make an observation outloud.  

Food Chain-Berries as producer  Food Chain diagram-Berries Producer


"Ok, so those of you with berries as your producer, which organism receives energy from them after eating them?"  Students share different animals. I add arrows from the berries and draw the different organisms  shared by students.  I point out that berries is a source of energy for more than one organism. We continue building a model on the board to show that one organism may serve as an energy source for variety of organism. When we finish, I point out the different food chains represented on the board. I explain that we have now created a food web.  

Then I project sample food webs (one at a time) on the board. I start off with a simple food web to illustrate the food chains that are embedded within it. Then I move on to more complex web. On each one, I point out that their are multiple chains represented in the web. I ask students to pick out different paths of the food web.

food web


I define it term more accurately sharing that a food web is made up of two or more food chains. The arrows show the direction of energy moving through an ecosystem and the energy relationships among organisms in a community.  I emphasize the importance of arrows in a food web when diagramming it. It is necessary to have accurate arrows showing the movement of energy from one organism to another.  And having multiple paths in a food web, arrows need to be clearly displayed. 


30 minutes

Creating Food Web

At this point, I have students become a group of four.  When they created their food chains yesterday, they each had their own chain of organisms that displayed the flow of energy from one to another.  I explain, "You are working as a group to create a food web. Your task is to analyze all four chains within your group and work to together combine them into one large food web." My intention is to have students recognize the similar organisms that are included in their group member's chains and arrange them using arrows to show multiple organisms can obtain energy from one another.  

I tell them to identify the similarities among the food chains, I have them to start with the producers, find all the producers used, then build from there. I remind them that if different consumers obtain energy from that one producer, they need to show it by drawing multiple arrows from the producer to the consumer eating it. Once they determine those consumers obtaining energy from the producers, I have them analyze the remaining organisms and discuss the next organisms to be part of their web. This continues until the feel they have a completed food web.

Misrepresentations and Confusion

While students are working, I circulate the room listening to plans and identifying the different webs being created. I check in with groups throughout the task. I notice missing arrows and some with many arrows.  While they have multiple paths displayed, I point out some connections on their web that should have an arrow to show the flow of energy moving through their web. 

As I continue with groups, I realize there are a lot of misrepresentations as they are working so I reconvene the class as a whole. I try to clarify some inaccuracies I noticed. For example, many groups were using all the cards that everyone had brought to the group from their original chain, so the same organism was appearing more than once on the web.

food wb student sample

I explained that multiple arrows coming from the one organism would illustrate the multiple ways energy from that one source is passed on.  

Review and Redo- Staircasing the Concept 

At this point, I have the students stop their webs. I decide to guide them through creating this web. First I project a food web from earlier in the lesson. I use it to remind them how the organisms appear once and that the arrows are showing the movement of energy between them. Then, I walk them through creating a web with the organisms by having them create simple food chains with their cards This way, if they decide to have the same organism used more than once, they would use the arrows to show the connection.

I start them off by asking them to select a producer to work and look at all the consumers that might consume the energy from that producer.

I have them select three consumers and place it on their poster. I explain that the producer passed on energy to these three consumers, so now think about what the next organism might be in each of these chains. I continue to gradually release the task until they have a completed food web

food web student sample

What would I do next time?

Next time, I would hand out a new set of cards to be used. This would ensure that each organism is represented and the focus would be more on using the arrows to show the flow of energy moving through the system. I would also have students highlight or color each food chain within the web with different color. This would be a better visual of the many food chains within the web. Then I would have the students pick one of the food chains displayed in their food web and have them visualize it happening in an ecosystem. They would write a small narrative about it. This narrative would illustrate the movement of energy in a system. It would include the sun shining down, for example, on the trees (or any producer they have in the web) and using it for photosynthesis. Then, they would write about a herbivore like a caterpillar and how it eats some of the leaves on the tree. The narrative would continue with the herbivore moving on, walking, crawling, or slithering through the soil and over rocks, and eaten by another consumer. The narrative would end with a tertiary consumer's role in eating this consumer.  

Having them construct a written piece would help them process and synthesize the flow of energy through a system. Furthermore, it would make concept more concrete.


20 minutes

How Do Food Webs Change?

With our food webs in front of us, I ask students think about what would happen if one organism was removed from their food web. I want them to recognize that if an organism did not exist, that their diagram would change completely.  

To help students better understand this concept, I ask them to take out their energy pyramid from the roles in an ecosystem lesson. I explain that their pyramid will serve as a reference for identifying the types of consumers: primary, secondary, and tertiary. I ask them to think how their food web would change if the following happened 

  • What would happen if one of your primary consumers was killed off by a disease? How would that impact your food web?

  • What would happen if the one of your secondary consumers start to become extinct? What would happen to the producers in your web? What about the tertiary consumers in your web, how would that impact them?

  • What would happen if there were no decomposers?


To give students a more concrete idea about this concept, I project Chain Reaction on board. (I move past the vocabulary review and go to the fourth slide in the simulation)

Fourth slide in Chain Reaction

Here, I click on the forest food chain and engage the students in building a simple food chain. When we finish constructing together, the screen asks the question: What would happen if you remove the frog from this food chain?

Slide What happens if no frog?

We click on it to find out an explanation and recognize the significance of one organism within a food chain and its impact if it is removed.  

no frog

I move them on to the next model, the Northern Food Chain. We engage in the same process and discover what happen when the fish are removed from this food chain.

These two scenarios illustrate the how the flow of energy is disrupted and change and explains why populations increase and decrease within an ecosystem.

Applying the Concept

Using the same questions above, students are are asked to make connections of the concept to their food web. They should recognize that some populations will increase because that removed organism is not there to be eating them, while others decrease as a result.

I have students construct an explanation to these questions to explain the cause and effect if an organism is removed from their food web. They begin this in class and assigned for homework. I collect it the next day.