Lesson Plan

Living & Non-living Interactions

student examines a snail

NPS Photo

Overall Rating

Add your review
Grade Level:
Third Grade
Four 30-minute activities and one 45-minute post-trip lesson
in the park
National/State Standards:
Utah State Science Core Curriculum Topic, Standard Two: Students will understand that organisms depend on living and non-living things in their environment.
environment, living, non-living, interactions


Students examine the interaction of elements of the food chain - producers, consumers and decomposers - through dioramas and art projects in the classroom. In the field, a story and an active game reinforce predator-prey relationships. Students examine decomposers and their vital role in the nutrient cycle, then they investigate energy loss in the high desert food chain.


Pre-trip activity: All the Pieces
a. Describe the difference between living and non-living objects.
b. Define producer, consumer, herbivore and carnivore.

Station #1: Everything is Connected
a. Describe a simple food chain.
b. Name at least one producer, one herbivore, and one carnivore.
c. Name one non–living thing and discuss how it affects its ecosystem.

Station #2: All Things Dead or Alive
a. Describe the nutrient cycle.
b. List three decomposer organisms

Station #3: Who's For Lunch
a. Discuss the interplay of population and food supply in a predator-prey relationship.
b. List at least two causes of changes in the balance of nature

Post-Trip Activity: The Mask of Life
a. Define the terms producer, herbivore, carnivore, and omnivore.
b. Describe the proportions of a balanced ecosystem.


An ecosystem can be defined as all the living and non-living things in a given area and their interactions. The non-living things include climate (weather, temperature, rainfall), geology (rocks, soil type), and geography (location of vegetation communities, exposure to elements, location of food and water sources relative to shelter sites). Soil is often comprised of both living and non-living elements. Living elements can continue to aff ect the community even after they change to non-living substances. An ecosystem is commonly a large area and can include many square miles of land or water. It includes many interconnected habitats. The two most important things to emphasize about an ecosystem are that all the members (living and non-living) are connected and that changes in one habitat or organism cause changes in another. Some relationships between members are direct and obvious. Other relationships are not so obvious.

A natural community is composed of plants and animals living and interacting within an area that has similar physical characteristics throughout. A community is usually defi ned by and commonly named for its predominant vegetation. Communities in southeastern Utah include canyon-riparian, slickrock, piñonjuniper, sagebrush, blackbrush, and montane.

Within a desert ecosystem, there are many communities, which all respond to these basic conditions: not much water (aridity), hot summer days, cold winter nights, and wind.

A food chain represents the transfer of energy from the sun to living organisms. Producers are green plants that use the sun’s energy directly. Primary consumers (herbivores) feed directly on the producers. Secondary consumers (carnivores) feed on the primary consumers or other secondary consumers. Omnivores can be primary or secondary consumers.

Decomposers, such as bacteria, fungi, termites, and earthworms, are scavengers that feed on the organic material found in dead producers and consumers. They break down the organic material to the nutrient level. Nutrients in soils are essential for producers to grow. Nutrients include nitrogen, carbon, and phosphorous. Thus, dead consumers (and producers) are recycled back into new producers.

In every ecosystem, various food chains are interconnected in a food web. Food chains and food webs indicate the eating patterns of the members of an ecosystem. Each component of the food web is necessary for the health of the ecosystem as a whole.

Any food web or food chain is a system that transfers energy from the sun. Each link in the chain depends on the link below it. Producers incorporate the sun’s energy and, in turn, are eaten by herbivores. Herbivores are eaten by carnivores or omnivores. Ninety percent of the energy is lost in each transfer, explaining why there are so many more producers than herbivores and so many more herbivores than carnivores. A food pyramid, with producers at the bottom, primary consumers in the middle, and secondary consumers at the top, illustrates this concept.



Post-Trip Activity: The Mask of Life

Materials poster of animals; bucket; category cards (11 cards labeled producer, 6 herbivore, 3 omnivore, 1 carnivore, and 4 decomposer); blank masks; craft sticks; construction paper; glue; markers; scissors.

1) In the classroom, review the defi nitions of ecosystem, producer, herbivore, carnivore, omnivore, decomposers, living things, and nonliving things.

2) Tell the students that they are going to become living things in an imaginary ecosystem. Discuss how everything interacts. Ask the students to name some creatures they might find in the desert ecosystem. Write answers on the board in the appropriate category (herbivore, carnivore, etc.) Ask the students to predict how many things out of each category they would expect to fi nd in an ecosystem of twenty-five living things. Write the answers on the board. Tell the students that the ecosystem they are going to make is similar in proportion to a real ecosystem and that there will be similar numbers of creatures. Explain that they will each pick a card out of a bucket that has a category written on it. Once they get their card, they get to choose an animal in that category to become (they can either look at the list on the board or the animal poster for their choices). Show the students the animal poster. Walk around, letting each student pick a card from the bucket. As you collect the cards, make sure all the children have picked an animal. Tell the students that they get to become their animals by making masks.

3) Show them examples of masks made for some of the animal choices. Distribute blank masks, craft sticks, construction paper, markers, scissors, etc. Give students about 15 minutes to make their masks.

4) Tell the students that it is time to see how many different things are in our imaginary ecosystem. Ask the students who are producers to hold their mask and stand up at their desks. As a class, count how many there are, and record the information on the board. Discuss how their predication diff ered from the actual number of producers in the ecosystem. Repeat with the other categories of animals. Ask the students how they could conduct a similar experiment in the natural world. 


Have students place their masks on a large wall mural depicting the desert food web.

Additional Resources

  • Bender, R. (1994) The most unusual lunch. Dail Books.
  • Brady, I. (1998). The redrock canyon explorer. Talent, OR: Nature Works.
  • Caduto, M. & Bruchac, J. (1988). Keepers of the earth: Native American stories and environmental activities for children. Golden, CO: Fulcrum.
  • Cornell, J. (1979). Sharing nature with children. Nevada City, CA: Ananda Publications.
  • Daugs, D. R. (1992). Foundations in science for elementary teachers. Logan, UT: Utah State University.
  • Storer Camps. (1988). Nature’s classroom: A program guide for camps and schools. Martinsville, IN: American Camping Association.
  • Tweit, S. J. (1992). The great southwest nature factbook. Bothell, WA: Alaska Northwest Books.
  • Van Matre, S., Johnson, B., Soloway, E., & Bires, F. (1987). Conceptual encounters I. Warrenville, IL: The Institute for Earth Education.
  • Williams, D. (2000). A naturalist’s guide to canyon country. Helena, MT: Falcon Publishing.


environment, interaction, living, non-living, organism, survive, observe, terrarium, aquarium, temperature, moisture, small–scale