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Food Chains and Food Webs

Grade Level: 6-8

Time Frame: 40-45 minutes

Introduction to Lesson: 

This lesson provides students with the opportunity to learn about food chains and webs, and to apply that knowledge to an exploration of the effects of the invasion of North American wetlands by Phragmites.

New Jersey Core Curriculum Content Standards


Strand B: Diversity and Biological Evolution

Cumulative Progress Indicator 2: Discuss how changing environmental conditions can result in evolution or extinction of a species

STANDARD 5.10 (Environmental Studies) All students will develop an understanding of the environment as a system of interdependent components affected by human activity and natural phenomena.

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STANDARD 3.1 (Reading) All students will understand and apply the knowledge of sounds, letters, and words in written English to become independent and fluent readers, and will read a variety of materials and texts with fluency and comprehension.

H. Inquiry and Research

·          Summarize and organize information by taking notes, outlining ideas, and/or making charts.

STANDARD 3.2 (Writing) All students will write in clear, concise, organized language that varies in content and form for different audiences and purposes.

A. Writing as a Process (prewriting, drafting, revising, editing, postwriting)

·          Write informational compositions of several paragraphs that engage the interest of the reader, state a clear purpose, develop the topic, and conclude with a detailed summary.

·          Use strategies such as graphic organizers and outlines to elaborate and organize ideas for writing

·          Understand and apply the elements of a scoring rubric to improve and evaluate writing.

·          Reflect on own writing, noting strengths and setting goals for improvement.

C. Mechanics, Spelling, and Handwriting

·          Use Standard English conventions in all writing, such as sentence structure, grammar and usage, punctuation, capitalization, spelling, handwriting.

·          Use a variety of sentence types and syntax, including independent and dependent clauses and prepositional and adverbial phrases, to connect ideas and craft writing in an interesting and grammatically correct way.

·          Use knowledge of English grammar and usage to express ideas effectively.

·          Use correct capitalization and punctuation, including commas and colons, throughout writing.

·          Use knowledge of roots, prefixes, suffixes, and English spelling patterns to spell words correctly in writing.

·          Edit writing for correct grammar usage, capitalization, punctuation, and spelling.

·          Use a variety of materials, such as a dictionary, grammar reference, and/or internet/software resources to edit written work.

·          Write legibly in manuscript or cursive to meet district standards.

STANDARD 9.2 (Consumer, Family, and Life Skills) All students will demonstrate critical life skills in order to be functional members of society.

A. Critical Thinking

·          Communicate, analyze data, apply technology, and problem solve.

C. Interpersonal Communication

·          Demonstrate respect and flexibility in interpersonal and group situations.

·          Organize thoughts to reflect logical thinking and speaking.

·          Work cooperatively with others to solve a problem.

·          Demonstrate appropriate social skills within group activities.

·          Practice the skills necessary to avoid physical and verbal confrontation in individual and group settings.

·          Participate as a member of a team and contribute to group effort



Students will demonstrate the idea that organisms within ecosystems are connected by flows of energy from the sun to plants, and from there to animals by flows of energy and materials from prey to their predators. 


Students will recognize the interconnectedness of living things within ecosystems.   


Students will be able to describe some of the main effects of invasive Phragmites on a Marsh Food Web.

Materials and Resources:

1.      PowerPoint   (file in pdf format)

2.      Index cards telling students about the animal plant or other part of the food web they will be playing within the simulation.   Pdf format;   publisher format  (Note: many of these are the same animals and plants as seen in the marsh ecology unit.  However only animals and plants of a freshwater marsh were included in the flashcards here, whereas both species from freshwater AND brackish environments are included in the marsh ecology flashcard set).

3.      Ball of string cut into a variety of lengths

4.      Reference materials to allow students to learn about their species’ role within the marsh ecosystem


Anticipatory Set:  Teacher will ask students questions including:

1.      What is a species?

2.      What is a food chain?

3.      What’s the difference between a food chain and a food web?

4.      Where does all the energy that drives ecosystems originally come from?

Sequence Instruction:

1. Teacher will give a brief PowerPoint on food chains and food webs (15 minutes).

2. Students will take notes in their notebook on food chains and webs during the PowerPoint.

3. Teacher will assign students to be part of a food web (sun, different kinds of producer, different kinds of primary, secondary and tertiary consumer, detritivore etc.).

4. Teacher will give students time (about 10 minutes or whatever teacher feels necessary) to use textbook and other materials provided to write a one-paragraph informative essay about their part in the food chain including what they are, if they are sun, producer, etc., and how important they are to the food chain. (ALL PARTS OF THE FOOD WEB ARE IMPORTANT; the intention here is help students to fully understand this.)

5. After students complete their paragraphs the teacher will ask the person who is playing the sun to stand up. The teacher will pass this person a series of strings (one for each producer in the group) and will tell them to read their informative essay. The teacher will then ask the producers to stand up.  As each reads their essay a strand of string should be passed from the sun to each producer and the teacher will explain that this string represents the flow of energy from the sun to the plants.  Once all of the producers have read their paragraphs, each primary consumer (or herbivore) should stand up and read his/her piece.  Strands of string should be provided to the producers and passed to each herbivore that might reasonably be expected to eat the plant that each student represents (this should mean that each primary consumer will likely be joined to more than one producer by a string).  Again, this represents the flow of energy from the plants to the animals.  However, now materials (proteins, sugars etc.) as well as energy are flowing from prey to their predators. The process of reading paragraphs and connecting prey with their predators with strings should continue for the secondary and tertiary consumers, omnivores and detritivores.  The result should be a complex tangle of strings interconnecting each student with the others in the group.

6. After all students are standing up, the teacher will ask the students to note and discuss how interconnected all of the components of a food web are with one another.    

7.  The teacher should now play the role of invasive Phragmites.  She or he will run a thread from the sun to themselves.  A string should then be run from the teacher to any animal which is able eat Phragmites.  The teacher will then “outcompete” most of the primary producers, eliminating them from the marsh.  The students representing the outcompeted native plant species will be told that they have been eliminated from the marsh by the non-native Phragmites.  All the strings running from those plants to an animal should be retained by the students playing the plants.  The students playing herbivores will then be told that they can only stay alive if they have energy (a string) coming in to them from a plant.  Any animal that no longer has any food species in the marsh will then also leave the group and sit down, taking any strings that ran between them and any other animals with them.  Continue this process until all of the different trophic (feeding) levels has been assessed.  The only species left will be those able to survive in the invaded marsh.  This will be a much smaller subset of species than was present in the native marsh.

8.  The teacher should engage the students in a conversation about what happened when the Phragmites invaded the marsh and what it meant for the plants and animals in the marsh.

Accommodations and Modification:

Students with physical disabilities may need help in holding on to the strings in this exercise, or in positioning themselves physically within the food web representation.  Teachers may want to assign aids to help those students and / or assign those students roles


Ask students to write the answer to one or more of the following questions on an exit slip:


What did the strings represent in this exercise?


Where did all of the energy come from in the ecosystem?


Did animals tend to eat only one food?


What happened to the other plants in the marsh when the Phragmites invaded?  


What happened to the animals in the marsh when the Phragmites invaded?  Why?  

Homework  / Extension Activity

Students should sketch a simple version of the food web developed in class.  In this sketch, arrows are used to show energy flow from the sun to plants, and then to show who is eating whom within the ecosystem.  Students should be reminded that their arrows should show the direction of the flow of energy, so if a muskrat eats a cattail, that would be shown in the sketch as cattail → muskrat. 

The components that students should use in their homework food web sketch are

monarch butterfly,  red-winged blackbird,  sun,  ground beetle, cattail,  great horned owl, mink, cattail moth,  muskrat,  earthworm, swamp milkweed


TEACHER FEEDBACK REQUEST:  We are always to working to improve these lesson plans. If you use this lesson plan, we'd love to hear from you with your thoughts, comments and suggestions for future improvements.  Please take the time to fill in our survey at .  Thanks!


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© 2009.  Jodi Sisk (Author), Louise Wootton and Claire Gallagher (Editors)

 Although the information in this document has been funded wholly or in part by the United States Environmental Protection Agency under assistance agreement NE97262206  to Georgian Court   University, it has not gone through the Agency's publications review process and, therefore, may not necessarily reflect the views of the Agency and no official endorsement should be inferred.

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