National Agricultural Literacy Curriculum Matrix

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It's a Dirty Job

Grade Level(s)

6 - 8

Estimated Time

Two 60-minute sessions, plus observations for two weeks

Purpose

In this lesson, students will create mini habitats to observe earthworm behavior and learn about the important role that earthworms play in decomposition and plant growth.

Materials

For each pair of students

  • One 2-liter plastic bottle
  • One small plastic water bottle (16 oz)
  • Scissors
  • One cup of sand
  • Two cups of soil
  • Two earthworms (purchase from bait shop, garden store, or online)
  • Piece of cheesecloth to cover top of bottle
  • Rubber band or string to secure cheese-cloth
  • Worm food
  • Brown paper grocery bag
  • Tape

For each student:

  • An Earthworm’s Dirty—but Important—Job worksheet
  • Earthworm Project Agreement 
  • Directions for Earthworm Habitat Construction and Observations

Tip: Ask students to bring plastic bottles, soil, and earthworm food from home if possible.

Essential Files (maps, charts, pictures, or documents)

Vocabulary

decomposer: an organism that recycles nutrients by breaking down waste and the remains of dead plants and animals

decomposition: to break down into organic matter; this process is performed by bacteria, fungi, nematodes, earthworms, and others

fungi: organisms that feed on dead and decaying matter. Examples include mushrooms and molds

habitat: the environment where a particular species lives

organic matter: material in soil made from the decomposition of plants or animals. It increases the soil’s ability to hold water and air and resist compaction

Background Agricultural Connections

This lesson is part of a series called, Too Much? Too Little? created to introduce middle school students to the connection between soil nutrients and the food they eat. The lessons consist of a series of demonstrations and hands-on experiments that show that plants require nutrients in certain quantities. The lesson series allows students to investigate soil properties, learn how to properly prepare fertilizer nutrient solutions, identify deficiencies in plant nutrients using a key, and much more. Other related lessons include:

Although they often go unnoticed, earthworms play a significant role in our lives. As decomposers, worms have the important job of recycling waste material into nutrients that plants can use to grow and provide food for people and other animals. As worms burrow through the soil, they ingest soil particles and obtain nutrition by digesting any dead plant or animal remains, fungi, and bacteria in the soil. Through this process, the worms mix up the soil, providing air spaces for roots and water to penetrate. Worm excrement, or castings, provide excellent fertilizer. This is why many home gardeners put worms into their compost piles.

If you have ever held an earthworm, you probably noticed that it was moist. Earthworms do not have lungs, they breathe through their skin, which must be moist in order for oxygen to dissolve and pass into their bloodstream. Earthworms need a cool, dark, moist environment. They do not have eyes but do have special receptor cells to sense ground vibrations and light. The rings on an earthworm’s body are called annuli. Tiny bristles called setae help the worms pull themselves through the soil. The lighter colored “bump” in the middle of the earthworm is the clitellum, the structure responsible for secreting mucous required for the worm to breathe, reproduce, and for protection as the worm burrows through rough soil. Worms have a special organ called a gizzard to help them grind up and digest the soil that they eat.

Earthworms come in a variety of sizes. The largest known earthworm species in Australia can reach nearly ten feet in length! Some worms live close to the surface of the soil, while others burrow six or seven feet deep.

Earthworms can be classified into three main groups based upon the soil areas where they prefer to eat and burrow.

  • The worms you find in compost piles are in the Epigeic group. Epigeic earthworms live in plant litter near the surface of the soil and need a lot of decaying organic matter to feed on. These worms are relatively small and can tolerate living in conditions with many other worms. This makes them well suited for composting.
  • Endogeic earthworms live in the upper-to mid-soil layers and feed on soil and decomposing organic matter. Endogeic earthworms don’t have permanent burrows.
  • Anecic earthworms are deep burrowing and have permanent burrows that can be spotted by little piles of worm castings at the soil surface. These worms are large and are often referred to as “night crawlers.” Anecic earthworms feed on decaying vegetation that they pull into their burrows from the topsoil.

Earthworms are hermaphrodites, meaning they have both female and male reproductive parts. After mating, earthworms lay eggs inside a cocoon covering that hatches in about two or three weeks, but this can vary depending on species and weather conditions. Baby worms are called wormlets and look like tiny pieces of thread when newly hatched.

In addition to improving soil and decomposing waste, earthworms are important food for a variety of animals such as birds, snakes, amphibians, rodents, and other small animals.

Interest Approach – Engagement

  1. Inform your students that you will be giving them a list of facts about one specific thing. Ask them to raise their hand when they think they know what you are talking about. 
  2. Use the following clues1:
    • They aerate the ground.
    • They are vital to soil health.
    • They can eat up to 1/3 of their body weight per day!
    • They are a source of food for animals like birds, rats, and toads.
    • They are typically only a few inches long.
    • They are capable of digging as deep as 6.5 feet.
    • They are commonly used as fishing bait.
    • They can also be known as "night crawlers" because they can be seen feeding above ground at night.
  3. What is it? A worm! 

Procedures

Several days before starting construction of the worm habitats, introduce the project to the class so students have time to gather materials from home. Have students bring plastic bottles, soil, and worm food as identified on the attached instruction sheet, Directions for Earthworm Habitat Construction and Observations. Students will work in pairs and should decide which partner will be in charge of providing the listed items from home.

During this introduction, brainstorm answers to the following questions with the class and keep a list of ideas on the board:

  1. What would the world look like without earthworms?
  2. What role do earthworms play in the ecosystem?
  3. What do earthworms eat?
  4. How do earthworms help plants?
  5. How do earthworms help people?
  6. What type of habitat do earthworms need?
  7. How can we turn our food scraps into fertilizer?
  8. How should worms be cared for during their stay in our earthworm habitats? (At the end of a two week period, worms will be released into the school garden).

Instruct students to transfer the notes from the class brainstorm onto the graphic organizer called, An Earthworm’s Dirty—but Important—Job. Also, have students fill out the Earthworm Project Agreement showing that they understand the rules for caring for the earthworms in the habitats the class will create. Discuss the rules as a class and collect the signed Earthworm Project Agreement.

Concept Elaboration and Evaluation

After conducting these activities, review and summarize the following key concepts:

  • Soil quality is important to the growth of our food.
  • Farmers maintain soil quality in many different ways. Earthworms are beneficial to the soil.

Variation

  • Instead of having groups of students create their own earthworm habitat, make one large worm habitat in an aquarium for the entire class to observe.

ELL Adaptations

  • This lesson employs hands-on activities and cooperative learning. Activities provide opportunities for students to exchange, write, and present ideas.
  • Provide a model of the finished worm hotel project so ELL students can see what their completed project should look like.

Important
We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!

 

Enriching Activities

  • Have students research and learn about earthworm anatomy. There are a number of free “virtual earthworm dissections” on the web.

  • Plant two identical plants in pots in the classroom. Place a few earthworms in one pot. Over the next several months, determine if there is any growth difference between the plant potted with earthworms and the one without. Be sure to keep the soil moist.

  • Use the Make Your Own Worm Bin instructions (located in the essential files) to create a classroom vermicomposting bin out of a recycled styrofoam cooler. Prepare the cooler ahead of time, and then have students add the bedding, worms, and vegetable scraps. Vermicomposting in your classroom is an effective way to engage students with a wide variety of science concepts.

Suggested Companion Resources

Agricultural Literacy Outcomes

Agriculture and the Environment

  • Recognize how climate and natural resources determine the types of crops and livestock that can be grown and raised for consumption (T1.6-8.g)

Education Content Standards

Within CAREER

Plant Science Systems Career Pathway

  • PS.01.01
    PS.01.01
    Determine the influence of environmental factors on plant growth.
  • PS.01.02
    PS.01.02
    Prepare and manage growing media for use in plant systems.

Within SCIENCE

MS-LS2 Ecosystems: Interactions, Energy, and Dynamics

  • MS-LS2-1
    MS-LS2-1
    Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem.
  • MS-LS2-2
    MS-LS2-2
    Construct an explanation that predicts patterns of interactions among organisms across multiple ecosystems.
  • MS-LS2-3
    MS-LS2-3
    Develop a model to describe the cycling of matter and flow of energy among living and non-living parts of an ecosystem.
  • MS-LS2-4
    MS-LS2-4
    Construct an argument supported by empirical evidence that changes to physical or biological components of an ecosystem affect populations.

Common Core Connections

Reading: Anchor Standards

  • CCSS.ELA-LITERACY.CCRA.R.1
    CCSS.ELA-LITERACY.CCRA.R.1
    Read closely to determine what the text says explicitly and to make logical inferences from it; cite specific textual evidence when writing or speaking to support conclusions drawn from the text.
  • CCSS.ELA-LITERACY.CCRA.R.4
    CCSS.ELA-LITERACY.CCRA.R.4
    Interpret words and phrases as they are used in a text, including determining technical, connotative, and figurative meanings, and analyze how specific word choices shape meaning or tone.

 

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