InTroduction • State Standards (pdf)
Nothing in nature is wasted! Embark on an exciting inquiry-based adventure to discover first hand how the natural processes of the Earth recycle and reuse life's essential elements. This exploration will uncover ideas on how nature's ways can be a model for our daily lives.
At the end of the field trip, students will have been introduced to several of the following concepts:
- Nutrients are essential to life.
- Nutrients are matter that all living things need to stay healthy.
- Nutrient cycling is occurring all around us and within us.
- Nutrient cycling is an ongoing process that includes decomposition, food webs, weathering, seasonal changes, life cycles and the digestive system.
- We are a part of this cycle and impact it.
- There are no new nutrients so they must be conserved and reused (i.e. nothing in nature is wasted).
- Nature is a model for how humans reuse and recycle nutrients.
- Learn how to use scientific equipment in order to uncover how nutrients cycle through an ecosystem.
- Use various observation skills to explore the natural world.
- Map the movement of nutrients through a natural system.
- Learn how to design a human system that models the way nature recycles nutrients.
Explanation: The term Nutrient is not easily defined. The meaning of this term varies depending on the context in which it is used. The term is often associated with nutrition, where it is used to describe the nutritional value of foods. Used in this context, nutrients are the vitamins, minerals, proteins, fats and carbohydrates that are contained within food that our bodies need in order to stay healthy. In Ecology and Biology the term is used to refer to the materials which all life is made from. All living organisms, from bacteria to whales, are made primarily of six elements, all in the same proportion: Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus and Sulfur. Most organisms require small, often tiny amounts of additional elements such as Iron, Copper and Iodine. Sixteen elements are required by all organisms. Most plants require a total of twenty-three different elements to flourish. These could all be described as "life materials".
There is a fixed amount of these life materials available for use on the Earth. These materials can neither be created nor destroyed. So, what is here on Earth is all that has ever been available and all that will ever be available. Therefore, in order for life to continue, these life materials must be continually recycled and used over and over by all life forms. In fact, life on Earth depends on the continual cycling of these materials through the air, water, soil, plants, and animals.
Every plant and animal alive on Earth this minute is made of life materials that have been used and reused by life over and over again. This sharing process is called Nutrient Cycling. In other words, every atom in your body has been part of other living bodies many times before. In a way, parts of you have already been everywhere on Earth. Parts of you have been in bacteria, parts in plants, and parts have been in dinosaurs.
Death is the central feature of Earth's nutrient recycling program. Organisms release all their nutrients when they die and are consumed by decomposers such as worms, insects, bacteria, and fungi. This process is called decomposition and is the key to the recycling of nutrients from "wastes" back into forms which can be used by plants. In turn, these plants may die and be eaten by decomposers or they may be eaten by animals such as insects, fish or mammals. These animals in turn may die and become food for decomposers or they may be preyed upon by other animals. So in other words, everything is food for everything else. One organism's wastes become another organism's nutrients. For example, every animal on Earth releases carbon dioxide as they breathe. To them, it's just a useless byproduct. But to every plant on Earth, that carbon dioxide is a necessary nutrient for photosynthesis and continuing life. The plants, in turn, release oxygen into the air, which is necessary for animals. Life on Earth is a balanced process of exchanging each other's leftovers for benefit.
Activity: Begin by familiarizing your students with the vocabulary words listed above. At Mosquito Hill Nature Center, we will explore how nutrients move through the environment and how nutrients are used and reused by all living things. Students should be able to answer the following questions:
- What are nutrients and where are they found?
- Why are nutrients essential to life?
- How does nature deal with the fact that there are no new nutrients?
- What are some ways nutrients move from one form to another? (i.e. decomposition, food webs, life cycles, water cycle, air cycle, digestive system, weathering, etc.)
Next, introduce the idea of cycles to your students by tracing the mineral calcium. Prepare six signs that can be worn around the neck. Assign one of the following to each sign: 1) TOOTH-calcium, 2) SOIL, 3) PLANT, 4) COW, 5) MILK, 6) PERSON. Begin with one student wearing the TOOTH sign (teeth are made of calcium). According to the story, the tooth falls out into the soil (at this point the student wearing the SOIL sign joins hands with TOOTH). Then a plant grows from the soil containing the calcium (PLANT joins hands with SOIL). A cow comes along and eats the plant containing calcium (COW joins hands with PLANT), and begins producing milk to which the calcium from the cow is transferred (MILK joins hands with COW). People drink milk using the calcium for their teeth and bones (PERSON joins hands with MILK and TOOTH completing the circle) which will eventually return to the soil to be used by plants which will be eaten by animals.
Objective: Earthworms are important decomposers, which can help break down organic wastes into nutrient rich fertilizer.
Explanation: A million of them could live in an acre of soil. They can eat their own weight in soil and organic waste every day. They’re both male and female, reproductively speaking. They breathe through their skin. They can’t see but they sense certain colors of light. Their waste is a nutrient rich organic fertilizer, which can help plants grow. They are fascinating. They are slimy. They are earthworms! What better way to interest your class in the process of decomposition and nutrient cycling then creating a worm bin (vermicomposting bin). Students can observe the magic of organic matter changing forms from "waste" to "resource" right before their very eyes. Creating and maintaining a vermicomposting bin will offer endless opportunities for hands-on inquiry while helping students understand some important environmental concepts. Through studying worms students will learn how decomposition works first hand. They will see how nothing in nature is wasted and how humans can design systems using nature as a design model to reduce our negative impacts on the environment and convert what is typically considered waste into a valuable resource.
Activity: The time required for this activity varies depending on what you choose to do. The potential exists to create a long ranging activity that extends throughout the year or it can be done as a short term observation requiring a couple of class periods.
For the short term activity you will need:
- several plastic 2-liter soda bottles
- black paint
- worm bedding materials (newspaper, coconut fiber, or dried leaves)
- approximately ¼ lb. of red worms for each container
- spray mister to dampen the worm bedding
- access to vegetable and fruit scraps
- drill with ¼ inch bit for aeration holes
For the extended project you will need:
- a medium sized colored plastic storage bin with lid
- same equipment listed above and 1 or 2 lbs. of red worms. (see attached worm bin instructions)
Create a vermicomposting bin: (Options: short term observations or extended project)
Short term observations: Use 2-liter plastic soda bottle painted black. Drill ¼ aeration holes spaced every 2 or 3 inches, including drainage holes on bottom of container.
Extended project: Use standard store-bought, colored plastic storage container. (give size) Drill ¼ inch holes every 3 or 4 inches around sides and on bottom.
Bedding: Regardless of container size fill bin ¾ full with damp bedding materials such as shredded newspaper (1 inch strips), dead leaves, or coconut fiber (coir). Add a handful of soil to provide the grit that worms need to digest food. Bedding materials should be moist but not wet: about like a wrung-out sponge. Fluff up bedding so it does not become matted.
Worms: Redworms (Eisenia foetida), commonly known as red wigglers or manure worms are best. You can obtain worms from a bait and tackle shop or through "Gardening with Kids" (www.kidsgardening.com) or through the "Worm Digest" web site (www.wormdigest.org). One pound of worms (approx 1,000) will process 3 to 4 pounds of food scraps per week.
Worm Food: Worms can eat up to their own weight in food every day. Keep it vegetarian, providing veggie and fruit scraps (worms don’t mind if its rotting), pulverized egg shells (for calcium), coffee grounds, and tea bags. Avoid meats, dairy products, and oily foods.
Location: Locate worm bin in the classroom or outdoors. In either case, temperatures should remain between 40 and 80 degrees. If bins are outdoors keep them out of hot sun and heavy rains.
Feeding: Have your young scientists feed the worms slowly at first, gauging whether the food balance and moisture content seem adequate or needs to be adjusted. It’s a good idea to divide the larger bins up into 4 or 5 sections, then bury the food in a different section of the bedding each week. The worms will go to the food. When adding the scraps bury them under several inches of bedding, then place several sheets of damp newspaper on the surface to discourage fruit fly infestations. If you do notice any fruit flies, discontinue feeding scraps, remove all rotting fruit parts and instead feed the worms corn meal until the flies are gone.
Harvesting castings: After several months when most of the bedding has been transformed into dark, rich compost, you’ll need to separate the worms from the castings. One way to do this is to spread out a large sheet of plastic and dump the worm bin contents out under strong lights or in the sun. Form the castings into a couple of cone shaped piles and let sit for several minutes. Then scrape the outer inch or so off the cones until you start seeing worms. Then allow the cone to sit for a few more minutes while the worms continue to move away from the light toward the center of the pile. Eventually you will be left with a mass of worms in the center, which you can place into fresh bedding back in the worm bin.
Using the worm bin:
1. Have students maintain a log of the bin noting date of feeding, quantities and type of food, what section the food was placed in, moisture content of box and any observations or notes they notice.
2. Worm observations. Have small teams of students observe a worm and record their observations. Have them share what they observed and brainstorm a list of things they would like to discover about worms. Using their ideas, have each group design an experiment to discover something new about their worm. Hand out the "Worm Observation Worksheet" to guide them. Students may need some help brainstorming and designing experiments. Help students determine if their question is answerable within the time frame you designate.
3. Before they begin, ask each team to review their experiment with you. Help them gather the necessary supplies. Some possible worm experiment ideas: Do worms like it wet or dry? Do worms prefer darkness or light? Can worms see or sense different colors? (use flashlight with different colored cellophane over light) Is there a top and a bottom to a worm?
4. Have students perform their experiments and record the results. Bring the class together to share and discuss experiments, methods and results.
5. Extensions: Have students share information they learned about worms through rap, songs, and poems or create a puppet show by making worm puppets from socks.
Key Vocabulary Words for Worm Activities:
- Vermicomposting - method of composting which uses worms to help decompose food scraps, turning them into nutrient rich fertilizer.
- Worm castings - nutrient rich deposit left by the worm after its food has based through its digestive system. Can be used as organic fertilizer for plants.
- Clitellum- ring around the worm that produces a slimy collar which rolls off the head of the worm forming a little cocoon around the worm eggs
- Setae - bristles on segments which help worms hold on to the surrounding soil.
- Gizzard - where food is ground up for digestion through a combination of strong muscles and bits of grit from the soil.
*Used with permission of Riveredge Nature Center in Newburg, Wisconsin.