Pre-Visit Activity : Decomposition Terrarium
Third - Fifth Grade Online Curriculum : Communities

MAIN
Focus Question
Are worms important to plants?

Activity Synopsis
Students will conduct an experiment in which they observe:

  1. the rate of decomposition of different organic and inorganic materials 
  2. the effect that worms have on the rate of decomposition of these materials and on soil quality 

Time Frame
The initial set-up of the experiment will take approximately three one-hour periods. Less time will be required if worm "recycling centers" are constructed prior to first class session. You may want to consider constructing worm recycling centers outdoors to reduce clean-up. Worm recycling centers should be observed once a week for one month. Observations should be recorded. Each observation recording session will take approximately twenty minutes.

Student Key Terms

Teacher Key Terms

OBJECTIVES
The learner will be able to:

STANDARDS

Grade Level

Standards

3rd Grade

3-1.2, 3-1.3, 3-1.4, 3-1.7, 3-2.1, 3-2.2,
3-2.3, 3-2.4, 3-2.5

4th Grade

4-1.2, 4-1.3, 4-1.4, 4-1.6, 4-2.5, 4-2.6

5th Grade

5-1.1, 5-1.2, 5-1.3, 5-1.4, 5-1.6, 5-2.2,
5-2.4, 5-2.5
* Bold standards are the main standards addressed in this activity.

Third Grade Indicators

3-1.2 Classify objects or events in sequential order.
3-1.3

Generate questions such as “what if?” or “how?” about objects, organisms, and events in the environment and use those questions to conduct a simple scientific investigation.
3-1.4 Predict the outcome of a simple investigation and compare the result with the prediction.
3-1.7

Explain why similar investigations might produce different results.
3-2.1

Illustrate the life cycles of seed plants and various animals and summarize how they grow and are adapted to conditions within their habitats.
3-2.2

Explain how physical and behavioral adaptations allow organisms to survive (including hibernation, defense, locomotion, movement, food obtainment, and camouflage for animals and seed dispersal, color, and response to light for plants).
3-2.3 Recall the characteristics of an organism’s habitat that allow the organism to survive there.
3-2.4

Explain how changes in the habitats of plants and animals affect their survival.
3-2.5 Summarize the organization of simple food chains (including the roles of producers, consumers, and decomposers).

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Fourth Grade Indicators

4-1.2

Use appropriate instruments and tools (including a compass, an anemometer, mirrors, and a prism) safely and accurately when conducting simple investigations.
4-1.3

Summarize the characteristics of a simple scientific investigation that represent a fair test (including a question that identifies the problem, a prediction that indicates a possible outcome, a process that tests one manipulated variable at a time, and results that are communicated and explained).
4-1.4

Distinguish among observations, predictions, and inferences.
4-1.6

Construct and interpret diagrams, tables, and graphs made from recorded measurements and observations.
4-2.5

Explain how an organism’s patterns of behavior are related to its environment (including the kinds and the number of other organisms present, the availability of food and other resources, and the physical characteristics of the environment).

4-2.6

Explain how organisms cause changes in their environment.

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Fifth Grade Indicators

5-1.1

Identify questions suitable for generating a hypothesis.
5-1.2

Identify independent (manipulated), dependent (responding), and controlled variables in an experiment.

5-1.3 Plan and conduct controlled scientific investigations, manipulating one variable at a time.

BACKGROUND
Key Points
This section will give you the main information you should know to teach the activity.

Detailed Information
This section gives more in-depth background to increase your own knowledge, in case you want to expand upon the activity or you are asked detailed questions by students.

South Carolina is home to many different species of worms. Some are carnivores, like the aquatic chaetognaths, with protrusible jaws that are used to capture prey. Many worms that live on land, like earthworms, and many that live in the water, like ice cream cone worms, are decomposers and recycle nutrients by ingesting soil or mud and pieces of non-living organic matter (like pieces of leaves, grass clippings, salt marsh grass), and returning those nutrients to their communities through the process of defecation. Worms enrich the soil or mud in the community in which they live by recycling nutrients from organic material that would otherwise be unavailable, and returning them to the soil. By creating vast networks of tunnels that help air and water to reach other soil-dwelling decomposers (millipedes, centipedes, bacteria, beetles), worms help to speed up the rate of decomposition. Believe it or not, more than 5 billion organisms may be contained in a single cup of soil!

All of the organisms that inhabit a particular area comprise a community. Within a community, decomposers, like earthworms, depend on plants. Non-living pieces of plants (leaves, fallen tree trunks) provide food for decomposers. Likewise, plants depend on decomposers. Plants are producers and can harvest energy from the sun to make their food. This is done through the process of photosynthesis. However, terrestrial plants also need to uptake minerals from the soil using roots in order to survive. Decomposers provide these essential minerals to plants in a form that the plants can use. Because plants depend on decomposers, decomposers play a key role in food chains (and food-webs) in both terrestrial and aquatic systems. Producers depend on decomposers and consumers (herbivores, omnivores and carnivores) depend directly or indirectly on plants.

A population of organisms consists of all individuals of a species that occur together at a given place and time. Each worm recycling center will contain its own population of worms. All of the different populations that are living in the same place and the physical factors with which they interact compose an ecosystem. Each worm recycling center will be an ecosystem created by soil, water, and non-living organic and inorganic material (the physical factors), a population of worms and possibly an array of other living organisms. A niche is the role an organism plays in its community or ecosystem; in the worm recycling centers the worms play the role of decomposer. Students can observe how worms speed the process of decomposition and enrich soil by placing worms in containers that house a variety of organic and inorganic material. The worms, in addition to bacteria and fungi, will begin to decompose the organic and some of the inorganic materials. The rate of decomposition of each material will depend on its molecular make-up. Those materials, like vegetable scraps, coffee grounds, and grass clippings, with a carbon to nitrogen ratio close to 30:1 will be decomposed the fastest. Students should observe how the worms cause change in the environment in which the worms are living. Inorganic materials, like plastic and Styrofoam, take hundreds of years to decompose. Thus, students will observe no change over time in the appearance of inorganics and should be encouraged to think about or discuss the ways in which humans cause change in the environment where they live.

South Carolina Aquarium Spotlight Organism: The Earthworm
Horticulturalists at the South Carolina Aquarium love earthworms! Why would someone who takes care of plants really get into earthworms? Well, here is the scoop.

There are more than 3,000 species of earthworms and earthworms live almost everywhere that there is moist soil. One acre of cultivated land may be home to as many as 500,000 earthworms, each making the soil a better place for plants.

The four-inch long, pale red garden worm is often called nature's plow. The earthworm pushes through soft earth with the point of its head. If the soil is hard, the worm eats its way through, forming interconnected burrows, some several feet deep. Earthworms, like chickens, have a digestive system equipped with a gizzard. A gizzard is a sac with muscular walls. The muscles of the gizzard, combined with mineral particles and very small stones ingested by the earthworm, help to grind food thoroughly. Burrows loosen the soil, admitting air and water and helping roots grow.

As an earthworm feeds, organic matter passes through its body and is excreted as granular dark castings (fecal matter). You may see these small casting piles in your garden. An earthworm produces its weight in castings daily. Wormcasts are rich in nutrients otherwise unavailable to plants. When you add nitrogen-rich compost to your soil, you help worms. An earthworm's body is 72% protein, so it requires lots of nitrogen (the building blocks of protein) to maintain itself. However, adding synthetic nitrogen fertilizers may repel earthworms. Worms are sensitive to physical and chemical changes and will flee the salty conditions that result from an application of chemical fertilizer. Earthworms will not burrow into soil with a pH below a certain level, which varies from species to species. Acid-sensitive nerve fibers are present all over the body. Thus, earthworms can be used as bioindicators (1).

The effects of earthworms on the soil are many. Both the castings, which become mixed with the soil, and the open channels created by burrowing ease the downgrowth of roots and enhance the fertility of the soil by increasing aeration and increasing drainage. The thorough grinding of soil in the gizzard is an effective kind of soil cultivation. When earthworms are present in the soil, agricultural productivity is generally higher, and in some cases greater crop yields have been achieved by introducing earthworms into soils (2).

Earthworms are segmented and their bodies look like a series of attached rings. Each segment of an earthworm contains four pairs of bristles. These bristles aid the worm in locomotion and also can make it very difficult for a bird or a curious human to pull it out of its burrow.

Earthworms, like seastars, are also capable of regenerating lost body parts. Both the head and the tail of an earthworm can be regenerated, within limits. The extent of regeneration depends on the species, as well as on the position of the "wound" and the size of the worm fragment that remains (2).

Life cycle:
In cold weather, a soil search will turn up mature and young earthworms as well as eggs. By late spring, most worms are mature. As temperatures rise, activity slows; many lay eggs and then die. By midsummer, most worms are very young or protected by egg capsules. As the weather cools, young worms emerge. With wet weather, they grow active, making new burrows and eating extra food, resulting in more worm casts. Egg laying again occurs. Activity continues as long as soil stays damp.

After a heavy rain, earthworms often appear above ground. They haven't drowned. Fresh water doesn't disturb earthworms--they need ongoing skin moisture to breathe--but stagnant or contaminated water forces them from their burrow(1).

Earthworms are hermaphroditic which means that each worm has a complete set of male and female body parts!

Earthworms are eaten by some snakes, centipedes, large beetles and birds (primarily the robin and the woodcock). The niche an earthworm fills in an ecosystem is as a decomposer.

Horticulturalists at the South Carolina Aquarium have added a species of earthworm, Lumbricus terrestus, to the soil in the mountain forest aviary. They know that the earthworms will help to keep the plants in the exhibit healthy.

  1. (Year). Bradley, Fern M., and B. Ellis. Rodale's All-New Encyclopedia of Organic Gardening: the Indispensable Resource for Every Gardner. Saint Martin's Press.
  2. (1987). Pearse, Vicki and J. Pearse et al. Living Invertebrates. Blackwell Scientific Publications and the Boxwood Press.

PROCEDURES
Materials

Procedure
Each student team will need two worm recycling containers. The following steps can be done prior to the first class session to save time, if needed:

  1. Remove the label from the plastic soda bottle.
  2. Cut the bottle into two sections; make the cut approximately one-third of the way from the bottom.
  3. Cover the mouth of the bottle with a square of pantyhose, cheesecloth, or handiwipe and secure the material to the bottle using a rubber band.
  4. Turn the top section of the bottle upside down and place it in the bottom section. Tape the two sections together with clear tape.
  5. Place one cup of sand in the worm recycling center.

Students should complete the following tasks:

  1. Ask student teams to closely observe the organic and inorganic materials in their terrarium to formulate descriptions of how they appear.
  2. Students should record these observations in writing or through drawings. If a Polaroid camera is available, take a picture of each material (pictures and/or descriptions will serve as a control so that one month later students can compare what the materials look like before and after the experiment).
  3. Ask student teams to predict which materials will decompose quickly and which will decompose slowly and to record their predictions.
  4. Ask each student team to choose one material to study in their experiment; ensure that within the entire class at least two different types of organic materials and at least one type of inorganic material are involved in experiments . You can also assign materials to teams to ensure that an array of materials is studied.
  5. Ask each student team to take one-half cup of soil and place it in a labeled Ziploc bag for future comparative study (this is a control sample so that students can compare the soil enriched in the worm recycling centers one month later to the soil sample taken at the beginning of the experiment).
  6. For each of the two worm recycling centers, student teams should then place two cups of soil on top of the sand, followed by one cup of organic or inorganic material. Repeat this until the soda bottle is three-quarters of the way full. The top layer should be a layer of soil. Students should use only one type of organic or inorganic material per container.
  7. Students should then add twenty worms to ONE of the containers. The other container should just contain a mixture of soil and organic or inorganic material. Cover the top of both containers with pantyhose and wrap with a rubberband. The "wormless" recycling center acts as a control to the recycling center with worms; students will be able to compare the contents of each container to determine what effect worms have on decomposition.
    *Students should add one cup of water to each recycling center and place the recycling centers where they will not be disturbed but are accessible for observation.
  8. Students should observe the recycling centers once a week and record their observations in their worm journals (see assessment).
  9. After students have recorded their observations, students should add one-half of a cup of water to their containers (containers need to be watered weekly).
  10. At the end of one month, students should pour the contents of each container onto a separate sheet of newspaper and spread out the contents using a stick.
  11. Students should walk around the room and observe the contents of each container. They should try to answer the following questions through their observations:
  12. You can ask students to record observations in their worm journals individually, in student teams or as a whole class.
  13. Students should return worms to a compost pile (most commercially bought worms are not capable of surviving in a garden).

ASSESSMENT
Assessment, A Language Link: A Worm's Journal
Imagine that you are an earthworm. You have been placed in a "worm recycling center" by a student.

  1. Use words and pictures to describe what you see as you travel through the recycling center on the first day.
  2. Use words and picture to describe how things have changed after two weeks.
  3. Use words and picture to describe how things have changed after three weeks.
  4. Use words and picture to describe how things have changed after four weeks.
  5. Use words and picture to describe what it might be like after a whole year.

Your finished product will be an earthworm's journal. As you record your observations and create your journal, remember to:

Scoring Rubric (Out of 6 points)

Cross-curricular Extensions
Art Extension
Have students create posters that show why decomposers are important to communities.

Social Studies
Have students research what happens to wastes in their area. Have them start a composting project in the school to take advantage of decomposers and to reduce the amount of wastes going to local landfills.

RESOURCES
Teacher Reference Books
Appelhof, Mary, Worms Eat My Garbage, Flower Press, 1982.
Provides information on setting up and maintaining worm composting systems.

Larson, Gary, There's A Hair In My Dirt!, Harper Perennial, New York, 1998.
This book provides a hilarious look at a maiden's view of the surrounding forest and the recycler's role in the habitat through the eyes of Father Worm. The book is not suitable for children but an excellent resource for teachers.

McLaughlin, Molly, Earthworms, Dirt, and Rotten Leaves, Macmillian Publishing Co., New York, 1986.
Examines the earthworm and its environment, also includes experiments.

Teacher Reference Websites
WormWoman
www.wormwoman.com
This web site provides detailed information on vermicomposting. What is it, how to start, and the benefits of using earthworms for composting are discussed.

The Yuckiest Site on the Internet
http://yucky.kids.discovery.com
This is a wonderful site! It provides kids with background information on earthworms and their job in recycling organic wastes. It also introduces children to five different worm species and their role in the environment.

The Compost Resource Page
www.oldgrowth.org/compost
Basic information on earthworms and vermicomposting is provided.

Student Reference Books
Glaser, Linda, Wonderful Worms, Millbrook Press, Connecticut, 1992.
Describes the physical characteristics, behavior and life cycle of common earthworms.

Henwood, Chris, Earthworms, Franklin Watts, New York, 1988.
Provides basic information on earthworms; body descriptions, building a terrarium and worm reproduction.

Lavies, Bianca, Compost Critters, Dutton Children's Books, New York, 1993.
Describes what happens in a compost pile and how creatures aid in the process of breaking compost into humus

Curricula
Aquatic Project WILD
Aquatic Project WILD is an interdisciplinary curriculum for K-12 teachers on aquatic wildlife and ecosystems. The activities cover a broad range of environmental and conservation topics. For information on signing up for workshops, call the South Carolina Department of Natural Resources at (803) 734-3814.

For more information click on:
www.dnr.state.sc.us/cec/educate/edu1.html#teacher

Project WILD
Project WILD is an interdisciplinary curriculum for K-12 teachers on a broad range of environmental and conservation topics. For information on signing up for workshops, call the South Carolina Department of Natural Resources at (803) 734-3814.

For more information click on:
www.dnr.state.sc.us/cec/educate/edu1.html#teacher

Field Trip Sites
Decomposers
Decomposers play a vital role in any wildlife community by breaking down dead organisms and waste material and by returning nutrients to the soil. The blackwater swamp is one of the best habitats to visit where the effects of decomposition are visible. The reddish black coloration of the water in a blackwater swamp is caused by the decomposition of leaves in the water. As the leaves decompose, they release tannins, which stain the water black. Below are listed sites where blackwater swamps and rivers are easily accessible for school groups.

If you are aware of other books, videos, websites, curricula, fieldtrip destinations or other materials that would make excellent resources for this activity, please e-mail them to us for inclusion in this list at: Education@scaquarium.org