LESSON 3: The Web of Life

SUBJECT: Science

OBJECTIVE: Students will become aware of the term "ecosystem" and will learn that all of life is interrelated in one way or another.

MEASUREMENT: Students will be able to visualize an ecosystem, and understand interrelationships in natural systems. They will know that agricultural crops like corn, livestock like pigs or cows, and humans, are also part of ecosystems.

BACKGROUND FOR TEACHERS:

"When one tugs at a single thing in nature, he finds it attached to the rest of the world."
- John Muir, American naturalist, explorer, and conservationist

STUDENT ACTIVITIES:

1. Ask students to read the story, Ann Learns a Secret Family Recipe. Ask students to discuss the paragraph in which she explains how everything is connected. "...good corn came from good soil, and good pigs came from good corn.meat from pigs was important to keeping her body healthy and strong." Talk about these relationships. Do the students understand where their food comes from? Do they understand the connection between corn and meat? Between soil and corn? (See Unit 2 for information about soil feeding corn.) Between corn and meat and themselves? Can they think of more examples where they are connected to soil, crops or animals?

2. Explain that an ECOSYSTEM is: a group of organisms and their physical environment, all of which interact through a flow of energy and a cycling of materials. (Example 1)

• The word "eco" comes from the Greek word "oikos" which means "home." See if the students can define the word "system."

• Ask students to study the ecosystem they see on Example 1, then to tell a story about it. Be sure they add a human to the ecosystem.

3. Divide the class into groups of eight to 10 students. Each group should sit in a circle. Give each student four lengths of yarn-each about five feet long-one blue (WATER), one green (FOOD), one white or yellow (AIR) and one brown (SHELTER).

4. Each group represents an ecological community. Depending on class size there may be more than one of each of the following communities. (Or older students might want to develop their own community roles.)

Pass out nametags with a role from the community for each student.

• Community 1: girl, stream, topsoil, oak tree, owl, trout, cow, cattail, worm, corn
• Community 2: corn, boy, pine tree, squirrel, frog, river, pig, fly, grass, topsoil

5. Explain that an ECOSYSTEM is: a group of organisms and their physical environment, all of which interact through a flow of energy and a cycling of materials. (Example 2)

• The word "eco" comes from the Greek word "oikos" which means "home." See if the students can define the word "system."

6. One by one, each student (role) needs to identify another student (role) to whom he/she is related by one or more of his/her basic needs-air, water, food and shelter. The student must identify why, then give one end of the length of yarn to the other to hold, thus connecting him/herself to the other.

• The topsoil provides food for the corn and trees and shelter for the worms. Soil is discussed in Unit 2). The corn and trees provide oxygen (air) through photosynthesis (See Unit 1, Lesson Plan ) and also provide plant residue that serves as food for the organisms in the soil. (Clean air is also discussed in Unit 7 ) Trees and grass (See Unit 2) shelter the topsoil. Trees are also shelters for wildlife and animals, and provide wood for shelters for people. Windbreaks made from trees can protect cornfields from storms. Children can build shelters for the animals, and can also protect the soil. Insects and their roles are discussed in Unit 3.

7. Several rounds of this will produce a distinctive colorful web of living relationships! See the following diagram.
(Example 2)

8. Ask students to portray this "Web of Life" in other ways: through writing, art, music or movement.

• Write a poem entitled "The Web of Life."

• Draw a picture entitled "The Web of Life."

• Write a play entitled "The Web of Life," including many of the above characters.

• Write an instrumental or vocal song entitled "The Web of Life."

• Choreograph a dance entitled "The Web of Life."

9. Take students on a field trip to a farm, or to a park, where they can explore the interrelationships that exist. Ask them to find a place to sit, then to record all the relationships they can see (including in the air) from that place. Ask them to keep a journal of their thoughts and feelings as they observe those relationships...

• Two "virtual" field trips are possible on the Internet. One, to see a farm ecosystem is found at
  http://topaz.kenyon.edu/projects/farmschool/nature/ecosys.htm .
  "Corn in the Farm Ecosystem" is at
  http://topaz.kenyon.edu/projects/farmschool/nature/corn.htm.
  and "Animals in the Farm Ecosystem" is at
  http://topaz.kenyon.edu/projects/farmschool/nature/cow.htm.

• Another site visits a hog farm: http://www.nppc.org/ForKids/farmtastic.html.

10. Ask older students to research human effects on ecological systems. (Unit 7 discusses use of plant-based energy and biodegradable plastics.)

Last reviewed May 7, 2004