Lesson 4

Plant ► Prey ► Predator


Lesson Overview:

Students will construct a variation of "Spinning the Food Web" to understand the components of ecosystems and their relationship to earth's greater environment.


Content Standards Addressed:
Common Core State Standards



Materials Needed:

  • Index cards.
  • Large sheet of yellow construction paper or a large yellow ball.
  • Colored yarn cut into 8-10 20-foot lengths.
  • A large ball of yarn (another color).
  • ​ ​


Reproducible: FYI! Habitats, Niches, Ecosystems

Make copies of the reproducible. Have students read the text and answer the Reflect and Review questions independently. Or read the text aloud and discuss the answers to the questions together.

Begin with a background discussion on the concepts of ecosystems, biodiversity and niches. Have students brainstorm as many different ecosystems as they can think of. Students should generate eight to 10 different ecosystems to use in the activity. Possible ecosystems might include:

  • Grasslands (meadow, prairie, savannah, etc.).
  • Rainforest (tropical or temperate).
  • Wetlands (freshwater or saltwater marsh, swamp, bog, pond, lake, etc.).
  • Ocean (barrier island, coral reef, deepwater, etc.).
  • Streams or rivers.
  • Desert.
  • Forests (deciduous, coniferous).


Reproducible: FYI! Forest Ecosystems

To provide students with background information on rainforests, deciduous and coniferous forests, make copies of the reproducible. Have students read the text and answer the Reflect and Review questions independently. Or read the text aloud and discuss the answers to the questions together.

When an ecosystem is suggested, ask the students what the nonliving components of the ecosystem are: What is the soil like? Where is the water? Is the air dry or humid? How much and what kind of precipitation falls here? What is the wind like? What is the geology (the rocks and land) like? What are the seasonal changes? 

Assign groups of three to each ecosystem and give each group three index cards. Also have three students act as ecosystem managers.​
With the help of reference books or reliable Internet sites, each group should find a plant, a plant-eater and a predator that lives in their ecosystem. They should write the name of the organism on the top half of an index card; on the bottom half they should identify their ecosystem.
Ask ecosystem groups to stand together, as all of the groups form a large circle. The ecosystem managers should stay on the outside of the circle.  

Place the sun - a large yellow circle or ball - in the center of the circle of students. Tape one end of each of the pieces of yarn to the sun.

Students should select the organism in their ecosystem that is most directly dependent on the sun for survival (they should identify the ecosystem's plant). Hand the "plant" student in each group the unattached end of the string. The strings now represent the rays of the sun.

Have each ecosystem group determine which organism receives the sun's energy next. The plant then passes the herbivore (plant-eater) the end of the string and moves towards the sun. The plant-eater now passes the string along to the organism that eats it - the carnivore (predator). At this point, all of the students should be holding part of their string.

Encourage groups to discuss what they are observing. How is everything in their ecosystem dependent on the sun? How are they dependent on each other? If the sun "goes out," what happens to the rest of the system? What happens when there are no plants? No plant-eaters? No predators? What other components in the ecosystem do their organisms depend on?

Now introduce the idea of ecosystem management. Have students debate whether ecosystems are better left undisturbed or managed. Why would people need to manage an ecosystem? How can managing an ecosystem protect biodiversity (removing invasive species, monitoring pollution, etc.)? Why is it important to preserve the biodiversity of an ecosystem?

Ecosystem managers should now enter the circle with the ball of yarn. Starting with one ecosystem, have the managers hand them the end of the yarn and ask, "All of the ecosystems are connected to the sun. How is your ecosystem connected to another ecosystem?" (Wetlands help keep pollution from the ocean; a swamp needs a nearby river to periodically flood, etc.) When the group decides on how they are connected, the manager should hand the yarn to the next ecosystem. Keep handing around the ball of yarn until students exhaust their answers.
The students should now have spun a large web in the center of the circle.
To expand the activity, have students select one organism from an ecosystem and declare it threatened. Discuss: What would happen to the system if this organism disappeared? What could we do to help that organism? What effect would helping on​e organism in an ecosystem have on other organisms in the system?
What would happen if a whole ecosystem disappeared? Have that ecosystem drop their strings to illustrate the effect it would have on other ecosystems.