Target Grade Level / Age Range:
2 hours plus additional observation time
Investigate the importance of earthworms in soil.
- small magnifying glasses (one per group)
- paper towels
- ruler (one per group)
- clean, clear 2-liter bottles (one per group)
- potting soil
- shredded newspaper
- grass clippings
- spray bottle with water (one per group)
- Red wiggler worms (2 per group)
Suggested Companion Resources (books and websites)
- Wiggly Earthworms by Natalie Lunis
Vocabulary (with definitions)
- Earthworm: long, segmented worm belonging to the phylum Annelida found in damp soil
- Invertebrate: animal without a backbone
- Vermicomposting: the product of the composting process of worms to create a mixture of decomposing vegetable or food waste, bedding, and worm castings.
Background – Agricultural Connections (what would a teacher need to know to be able to teach this content)
Earthworms are invertebrate animals in the phylum Annelida. Their bodies are made up of segments with small bristles which allows them to move and burrow through soil. Their bodies are charterized by a “tube within a tube” construction. An outer muscular body wall surrounds the digestive tract. As they burrow, then consume soil, and other decomposing organic materials. Earthworms are native to Europe, but they can also be found in North America and western Asia.
Living in the soil, worms provide many benefits! They tunnel in the soil, eat organic matter, and excrete castings. When the worms tunnel through the soil, water is better able to move through it. The soil also loosens up and allows oxygen and aerobic bacteria to get to the plant roots. Looser soil allows plant roots to penetrate deeper into the soil and gain access to more nutrients.
Earthworms also benefit the soil by providing fertilizer. They eat organic matter in the soil, digest it, and then excrete the contents as castings. The castings are an excellent source of nutrients for plants. Castings contain water soluble plant nutrients, organic matter, beneficial bacteria and enzymes.
Earthworms are powerful! They do more than aerate the soil and incorporate plant material into the soil, they also help improve soil structure. In order to do their jobs, they need two things- dead plants and to be left alone. Farmers leave crop residue on the ground after harvest. This creates a mat of organic material on the soil surface and will eventually start to decay. Worms will feed on the decaying residue and incorporate it back into the soil as nutrients that will be available to plants. When worms move throughout the soil they create tunnels that help aerate the soil. If the soil is tilled, then the worm’s tunnels are destroyed. To encourage Earthworms in the soil, avoid using deep tillage practices. This causes damage to the earthworm burrows that they created.
Earthworms can be used to create compost, this is called vermicomposting. Composting can be done anywhere- under your kitchen sink or in your garage, wherever you can store a bin. You can build your own worm bin using a plastic tub or build your own out of wood. You will want to use a container that has a depth between 8-12 inches. Worms like dark, moist environments. Vermicomposting bins should be stored in areas where the temperature is between 40 and 80°F. Worms are a lot like people, they do not like a lot of noise or vibrations and should be kept in areas away from high traffic.
A type of Earthworm called a red wiggler is a good choice to use when vermicomposting. They also reside near the surface of the soil, resulting in them turning over the compost components and quickly provide rich worm castings to be used as fertilizer. Red wigglers also reproduce more rapidly compared to other Earthworms.
Interest Approach or Motivator:
Hold up an Earthworm in front of the class. Ask students, “What is this? Where does it live? Do you think there are a lot of them? Do you think earthworms help farmers?” Complete a KWL chart about Earthworms.
Day 1: Complete an earthworm exploration ( 1 hour)
- Discuss the care and safety expectations of the earthworm.
- Pass out paper towels, small magnifying glasses, rulers, and earthworms to the partners.
- Have students make observations about the earthworms: Describe how they look, feel, and move. Which end is the head and which is the tail? How do you know? (First let them discover characteristics of the worm before you advise how to find the head/ tail end.) Instruct students to write observations in science notebooks. Use the magnifying glass to observe the worm more. Draw a picture of the earthworm in their science notebook.
- Measure the worm – Carefully demonstrate how to measure the length of the worm using a centimeter ruler.
- Clean-up and discuss observations. Read the book Wiggly Earthworms by Natalie Lunis
- Add new information to KWL chart
Day 2: Make an earthworm terrarium ( 1 hour)
- Put students in groups of two and pass out a 2-liter bottle for each group. Make sure the label is removed from the bottle, so students can observe the vermicomposting occurring inside. Clear bottles work best for observations.
- Cut the bottle ¼ from the top to allow easy access for inserting composting materials and worms.
- Add a layer of sand to the bottom of each bottle. Continue to alternate layers of potting soil, shredded paper, and grass clippings. Students should spritz each layer with a small amount of water using the spray bottle. Be careful not to over water. The contents should me moist, not wet.
- Once the layers are complete, add leaves on top layer.
- Add two Red Wriggler worms to the vermicomposting bin.
- Have students draw and describe their vermicomposting bin in their science notebooks. Have students write a hypothesis about what they think the worms will do in the terrarium within the next week.
- Wrap the terrarium in black paper and store in a cool, quiet place.
- Continue to make daily observations for a week and record observations/drawings in science notebook. After one week has passed, have students write their conclusion about Red Wriggler worms and vermicomposting.
- Discuss observations as a class and how these observations help plants and farmers. Continue to add to the KWL chart.
- Show the YouTube video: This Is What Happens When You Put Earthworms in Your Garden Soil video
Essential Files (maps, charts, pictures, or documents)
- This Is What Happens When You Put Earthworms in Your Garden Soil video
Did you know? (Ag facts)
- Earthworms are important to the soil and growing plants.
- 5,000 earthworms in one acre of soil can produce 50 tons of beneficial castings.
- Earthworms do not have lungs, they breathe through their skin.
- Each earthworm is both male and female, producing both eggs and sperm.
- An earthworm can eat up to a third of its body with in a day.
Extension Activities (how students can carry this beyond the classroom)
- Start a composting project for the school cafeteria.
- Wiggly Earthworms by Natalie Lunis (Book)
Iowa Agriculture Literacy Foundation
Agriculture Literacy Outcomes
- Agriculture and the Environment Outcomes:
- T1.3-5.d: Identify the major ecosystems and agro-ecosystems in their community or region
- Plants and Animals for Food, Fiber & Energy Outcomes:
- T2.3-5.c: Explain how the availability of soil nutrients affects plant growth and development
Iowa Core Standards
- 5-LS2-1. Develop a model to describe the movement of matter among plants, animals, decomposers, and the environment.
- Social Studies
- SS.5.5. With teacher direction, construct responses to compelling questions supported by reasoning and evidence.
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