MnSTEP Teaching Activity Collection > MnSTEP Activities > Investigation a food web: producers, consumers, and decomposers

Investigation a food web: producers, consumers, and decomposers

Sandra Ahlberg
Prairie Elementary
Worthington, Minnesota
Author Profile


Students will observe living things in a wooded area near the school. They will list all living things they observe in a journal along with a question about each observation. After returning to the school, students will be introduced to the vocabulary: producers, consumers, decomposers, and food web. Students will select a question that can be investigated and share with the class. The teacher will guide the class to use the same question to investigate. How do these living things affect each other? Each student will organize their data into the three categories of producers, consumers, and decomposers. Using one of their living things, they will create a food web with at least one living thing from each of the three categories. Students will predict what would happen if one of the living things in the food web became extinct or over productive. An extension will be to investigate living things at a wetlands area.

Learning Goals

This activity is designed for students to make observations, collect data, organize data, display data, and draw conclusions from the data. Students will use a science notebook to record their investigation.
Key concepts:
Consumers, producers, and decomposers affect each other in an ecosystem. If one of these living things is removed or increased, an imbalance will occur in the ecosystem.

-Food web

Context for Use

This is a field exercise that could take more than one day. One session is outdoors and a follow up session is in the classroom. It can be adapted for any ecosystem. Students will need a science notebook. You will need to find pictures of plants and animals in Minnesota for the sorting activity.

Subject: Biology:Ecology
Resource Type: Activities:Classroom Activity, Field Activity
Special Interest: Field-Based Teaching and Learning
Grade Level: Intermediate (3-5)
Theme: Teach the Earth:Enhancing your Teaching:Teaching in the Field

Description and Teaching Materials

Introduce students to the Wonder Wander investigation. You will take students to a wooded area, prairie, wetland, lake area, or park. Any place where they will see plants and animals. They are to set up a page in their science notebook to record observations. Have them make a T chart. On the left side, write the title: I observe (or I noticed, I saw). On the right side write the title: I wonder (these are questions about each observation).
Under the "I observe", they are to list all the plants and animals they see. Under the "I wonder" side write a question about the observation. Do not use "why" as a question.
Students should try to list 20 observations and questions.

After the Wonder Wander, return to the classroom. Students should select three questions they would like to investigate. Have them write their three choices on sentence strips. They will share their questions in a small group and then display them for the class. Introduce the question the class will investigate. How do producers, consumers, and decomposers affect each other in a food web?

Vocabulary: Add the vocabulary words, producers, consumers, decomposers, and food web, to their journals or vocabulary notebooks. Have them draw an example of each word by the definition.

Now they are to organize their list of data into the three groups: producers, consumers, and decomposers. Share with their group how they organized the data and discuss if they agree. They should check resources if they are unsure about the placement in a category. Make changes if necessary in their groupings.

Give each group pictures of plants and animals in different ecosystems in Minnesota. As a group, they will put them into the three categories of consumers, producers, and decomposers. They will then add these to their organized data in their journals.

They will then select one of their living things and make a food web including at least one consumer, producer, and decomposer.

Have students predict what would happen if one of the living things in their food web became extinct. What would happen if there was an over population of one of the living things? Share their predictions with one other person.

Take a look at a specific living thing in Minnesota: zebra mussels. Give each group information about zebra mussels. As a group, study the information and make a deduction of which category the zebra mussel is in (producer, consumer, or decomposer).
Share their reasons with the class. Make a food web that includes the zebra mussel.

Have students bring in pictures to display of producers, consumers, and decomposers.

Take a trip to a different ecosystem and repeat the activity. Compare and contrast the food webs of each ecosystem.

Teaching Notes and Tips

This activity is an inquiry that uses content from the science standards for 5th grade. In an inquiry investigation, you want students to come up with investigable questions. Hopefully, some of the students will come up with questions about what the living things they have listed eat. This will lead into the investigable question I have selected so that they will learn what the science standard requires. As an inquiry, they will decide how to organize their data and also to create the food web.

Decomposers may be the hardest part to list. You may have to add some of these to their lists. The Wander Wonder can be anywhere outside as long as there are some plants and animals. Select an area where students can sit and be quiet in order to observe animals.

Information about zebra mussels can be obtained from the DNR or the Bell Museum at the University of Minnesota.

In the past, we have toured a wetland and students did not list the living things they observed in a science notebook. This year, I will have them take their notebooks with them and list what they observe. They can also draw a picture of what they see.


Students will need to have a list of living things with questions in their science notebook.
Data should be organized into the three categories of producers, consumers, and decomposers.
There should be a food web with a prediction about extinction and over population.
There should be a food web with a zebra mussel in it.


Standard 5.I.B History and Nature of Science
Scientific Inquiry
The student will understand the process of scientific investigations.
Standard 5.IV.F.2 Life Science
Flow of Matter and Energy
The student will know that matter and energy flow into, out of, and within a biological system.
2. The student will use food webs to describe the relationships among producers, consumers, and decomposers in an ecosystem in Minnesota.

References and Resources