Food Webs

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Objective

SWBAT create an accurate food web for a given ecosystem when provided organisms that live in that ecosystem.

Big Idea

Students will determine which animals live in various ecosystems, then create a poster of a food web for one of the given ecosystems.

Rationale and Preparation

The Why Behind Teaching This: 

Unit 3 addresses standards related to the transfer of energy and matter between organisms in an ecosystem.  The unit begins with identifying what solar energy is and what two forms of energy solar energy provides life on Earth.  This is an important foundation for understanding standard 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.  We build on this knowledge throughout the unit in other lessons related to photosynthesis and how animals use the energy they get from food.  In this unit students will also be conducting experiments to gather evidence to support their belief that plants get the materials they need for growth from either water, air, or the soil.  This is covered in standard 5-LS1-1: Support an argument that plants get the materials they need for growth chiefly from air and water. Students will also be creating food chains and food webs to describe the movement of matter among organisms in an ecosystem.  This is covered in standard 5-LS2-1: Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.

I combined these three standards all into unit 3 because teaching them together allows students to see how they are all connected.  The energy that plants get from the sun is stored in their parts until animals consume them.  Plants cannot absorb this energy and reproduce without other materials from the environment such as carbon dioxide from the air, and water and nutrients from the soil.  The animals that consume the plants, use part of the energy for growth, reproduction, etc. but they also store some of the energy.  That energy is then passed on to other animals when they are eaten by other animals.  All of the energy that is available in an ecosystem can ultimately be traced back to the sun.  Teaching all of these standards together, instead of in isolation of each other, makes that connection easier to see.    

This specific lesson addresses standard 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.  By demonstrating knowledge that all food webs begin with a producer, students are demonstrating their understanding that the flow of energy through the ecosystem begins with the producer which originally got its energy from the sun.  It also addresses standard 5-LS2-1: Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.  Through creation of the food web, students are demonstrating their understanding that the energy and matter stored in organisms is broken down by decomposers once they die, and the nutrients put back into soil for plants to use again.  

Lesson Goal: 

The goal of this lesson is for students to be able to create an accurate model, in the form of a food web, to illustrate the transfer of energy through an ecosystem.   

Success Criteria:

Students will demonstrate mastery of this goal by creating a poster of a food web for a given ecosystem.  They will be assessed using the Food Web Poster Rubric.   

Preparing for Lesson:

Warm Up:

  • Envelope to put cards in for each group

Guided Practice: 

  • Science notebooks  
  • Copy of the food chain cards, cut, laminated, and magnet strips put on back. These were used in the previous lesson but will be used again to create a food web today. 

Explore: 

  • Copy of each set of the ecosystem cards from the warm up, not laminate.  
  • Large sheet of paper for each group 
  • Marker for each group to draw arrows on their poster 
  • Glue for each group 
  • Copy of the Identifying Food Chains within a Food Web worksheet for each group. 
  • Clipboard for each group 
  • Five copies of the Food Web Poster Rubric printed for me to use to assess each group. 

Wrap Up: 

  • No materials needed 

Warm Up

10 minutes

Introducing Types of Ecosystems 

I begin today's lesson with a card sort of organisms found in various ecosystems.  I do this for a couple of different reasons.  One purpose behind this introductory activity is to familiarize the students with animals that can be found in different ecosystems.  It also allows students to see the organisms in isolation before manipulating them to create food webs. I created sets from 5 different ecosystems because I have five table groups in my class. Each group will use one set to create a food web later in the lesson.  

I provide each table group with a laminated copy of organism cards from the 5 different ecosystems: Arctic Tundra Ecosystem CardsDesert Ecosystem CardsForest Ecosystem CardsFreshwater Ecosystem CardsOcean Ecosystem Cards.  I give the following directions before groups remove the cards from the envelope. 

  • Begin by placing the title cards at the top of the desks. 
  • There are 60 organism cards, 12 will be placed under each type of ecosystem. 
  • They do not have to be in any order, but all cards must be under the correct ecosystem to win. 
  • Everyone in the group must raise their hand and be sitting quietly before I will come check them. 
  • First group to have them all correct will win. 

Some of the organisms will be very easy to identify because their name has the the ecosystem in it.  For example, the arctic fox will be located under the arctic tundra.  Other organisms will be a little more difficult because they could be placed under several ecosystems.  For example, insects could be under forest, freshwater, and desert.  Students will be most successful if they save these for last, or pay attention to clues in the picture such as the background colors.  

   

After the first group gets them all correct, I tell everyone else to stop working and listen as I go over which organisms should be under each ecosystem.  I ask the winning group to explain how they were able to place them in the correct place.  What characteristics helped them identify the organisms from each ecosystem.  After they tell us some things such as fur color, terms in the name, etc.  I go over all organisms from each ecosystem and the other groups place them in the correct location.  This allows them to see where each belongs, not just hear it.  This helps the visual learners grasp the relationships. 

Guided Practice

10 minutes

 Adding Information in the Notebooks 

After students place the organisms in the correct locations, I ask them to mix them all up and put them back into the envelopes.  I collect the envelopes while students are getting out their science notebooks.  I place my notebook on the overhead to model what the notes should look like.  I do this mainly to help support ESE and ELL students, but it is also beneficial for those who struggle with writing and spelling as well as visual learners.  

I explain that there are various types of ecosystems, each with different types of plants and animals competing for food, shelter, and water to survive.  We discussed food chains yesterday so I review that they are one way to show how energy flows through an ecosystem.  I let students know that food chains only show a single path that energy is transferred but in an actual ecosystem, one animal may get energy from several different types of plants and/or animals.  We begin taking notes in the notebook. 

  • We title the page Food Webs 
  • We write the definition for food webs as a model used to illustrate several interconnected food chains within an ecosystem

We then create an example on the board using the yarn food chains created in yesterday's food chain lesson.  The models were created using the food chain cards provided.  One group created a food chain that showed energy being transferred from grass to the rabbit then to the snake and then to the hawk.  Another group created one that showed energy being transferred from the grass to the deer and then to the coyote.  These two chains are still taped to the board from yesterday.  I have a set of the food chain cards copied, laminated, and magnet strips put on the back. I put all of the organisms from these two food chains up on the board.  I arrange the grass, rabbit, snake, and hawk to create a food chain like the one created by a group yesterday.  I then ask the class what else gets energy from the grass except the rabbit and they tell me the deer.  I add the deer in by drawing a new arrow going from the grass to the deer.  I ask them what gets energy from the deer and they tell me the coyote.  I add it into the food web.  I then tell them that we can connect the food chains by seeing what other ways these organisms can get energy.  I ask them if there is anything on the board that may get energy from the rabbit except the snake.  One student says the coyote and another says the hawk.  I draw arrows going from the rabbit to these organisms.  I ask them if there is anything that might get energy from the snake besides the hawk and one student tells me the coyote.  

                                            

We draw this in our notebooks as an example but do so using words instead of pictures.  I then ask students to identify the individual food chains within this food web.  This helps students make the connection between the previous lesson and today's.  It also helps them see that although food webs look complicated, they are really just a bunch of simpler food chains connected.  By identifying the individual food chains, it would also be easier for students to trace the flow of energy back to the sun when asked to do so.  We came up with five food chains and recorded them in our notebook.

  • grass to rabbit to snake to hawk
  • grass to rabbit to hawk
  • grass to rabbit to coyote 
  • grass to rabbit to snake to coyote
  • grass to deer to coyote

                                                      

                                                                       Picture of Science Notebook Page 

Explore

30 minutes

Creating Food Web Posters 

I provide each group with one set of the ecosystem cards used in the warm up.  The set I provide them has not been laminated like those that were used in the warm up were. 

  • Group 1 - Arctic Tundra 
  • Group 2 - Forest 
  • Group 3 - Freshwater 
  • Group 4 - Ocean 
  • Group 5 - Desert 

I give each group  a large sheet of paper, a marker, and some glue.  I explain that they must use all 12 of the cards provided to create their poster and will be assessed on the accuracy of their food web once complete.  Groups spend the next 15 minutes creating their food web.  Once they have completed their poster they bring it to me and I hang it up somewhere in the room.  I spread out all posters so they are in all areas of the classroom.  

                                                      

Many groups made errors, especially with the direction they arrows point.  The last picture above shows energy going from the human to the bass, from the bass to small fish, then to krill and finally to the algae.  You can see that they did correct some of their mistakes by scribbling out the arrow on the line and adding it to the other end.  The group did not get them all corrected though. 

Gallery Walk

Once all posters have been hung up, I provide each group with an Identifying Food Chains within a Food Web worksheet and a clipboard.  Each group begins with their own poster and records all the food chains they can identify within their food web.  They have 3 minutes to do this.   Being able to identify each individual food chain is an important concept because it provides practice following the arrows to identify how organisms get energy within their ecosystem.  Being able to follow this flow of energy will help them be successful in tracing the energy back to the plant which gets energy from the sun. It also allows students to see that one organisms could get energy from several others, and it can provide energy to several others.  

After three minutes, I have groups rotate to the next poster.  Group one will move on to group two's poster, group two will go to group three's poster, etc.  I give them 3 minutes, then have them rotate again.  We continue this until all posters have been seen by each group.  While groups are completing the gallery walk, I circulate to fill out the Food Web Poster Rubric for each group.  I check each poster to see if all criteria is met and note any areas where mistakes may have been made.  At the bottom of the rubric, there is an area for me to note all of the food chains I see within each food web.  I will need this information to complete the last section of the rubric as well as determine if any group got them all listed during the gallery walk. 

You can see in the food web gallary walk video that groups assigned one recorder and then the other students in the group pointed out food webs.  Groups should have been rotating who was recorder so that all students had the opportunity to identify the food chains as practice for the assessment.     

Wrap Up

10 minutes

Group Accuracy 

When time is up for the gallery walk, all groups go back to their seats.  I write the name of each ecosystem on the board and ask groups to tell me how many food chains they identified in each.  We complete one at a time and after all groups tell me their number, I give them the correct answer based on my findings. 

I usually had one or two more then the closest group but in a couple of instances a group had one more then me.  Time was a big factor in the differences.  Some groups were not able to finish in the 3 - 4 minutes I was able to give them to record all of the food chains.  

       

To see these pictures more clearly: gallary walk lab sheet                          gallary walk lab sheet 2

The gallary walk sheets were a good assessment tool for me.  I was able to see the food chains that groups created and identify areas of weakness.  A couple of groups did not always begin with a producer and other groups did not use arrows.  Seeing these sheets provided me with useful information even if groups did not complete all the food chains.  

I show the class the set of food chains I have recorded on each rubric so that they can identify which ones they omitted from their list.  As I am showing the lists I ask students where the energy being transferred through the ecosystem came from.  They tell me it came from the sun.  I ask them what this energy is transformed into through the process of photosynthesis.  They tell me glucose or sugar.  I reiterate that the glucose produced by plants is used by the plant for growth and reproduction and is stored in the plant.  Animals that consume plants are using that glucose for energy to move, grow, and reproduce, and they also store energy that is passed on to whatever eats them.  We go through this for all five ecosystems as I show the individual food chains.  It seems repetitive to go over the same thing five times, but some students will benefit from hearing it five times.  It also allows me to call on many different students to make sure they can explain it.  If a student cannot explain it, I let them listen to others explain it a couple of times and then call on them again later. 

Providing Students with Feedback 

I pass back rubrics to each group so they can go over the information recorded.  I answer any questions and show them where their mistakes were on their posters.  The majority of students who received checks in the "No" column was due to not using all of the cards, or putting arrows in the wrong direction.