Earthworm Bridge

DESIGNED BY: Rogina Bolt, Brennen Elementary 

1) CORE CURRICULUM OBJECTIVE(S): Predict how living things may adapt structurally and behaviorally to changing environmental conditions.  (3SLS-8)

GRADE LEVEL: Third                  SUBJECT(S): Science

2) OVERVIEW: Students get a hands-on approach to one of our most basic decomposers - the earthworm. They learn the habits, adaptable traits and cognitive/instinctive mechanisms of this earthbound creature. They may gain a more empathetic approach to the lowliest of Mother Earth's living organisms.

3) FOCUS/ESSENTIAL QUESTION(S): What kinds of habitats do worms prefer? Will worms adapt behaviorally to changing environmental conditions? How?

4) TIME FRAME: Two fifty minute periods

5) RESOURCES/MATERIALS: For each group: ruler 10 redworms 2 thin, flat plywood pieces (6in. x 4in.) a large bin of water (should be at least 3/4 larger than the 2 plywood pieces) cheese cloth (enough to cover 2 plywood pieces) wooden support blocks 2 cups of moist compost soil Web site: http://www.nj.com/yucky/worm/ go to Teaching with Worms Books: Exploring Earthworms with Me: Simple and Fun Experiments to do with Earthworms by Jane Hoffman

6) CULMINATING ASSESSMENT: The teacher will give the following written test:

1. Do worms favor moist habitats or really wet habitats?
2. Will a worm cross a barrier to reach a desirable habitat?
3. Does the worm have the ability to learn and remember?

RUBRIC

7) INSTRUCTIONAL ACTIVITIES:

Procedures: (Concept Development and Exploration) Discuss with students the parts of a worm. Have students visit the listed web site. Have students look for sensory organs which might aid the worm in movement, seeing, smelling, feeling, etc.
1. Have students investigate worm behavior by testing for sensitivity to light, warmth, sound, touch, moisture, etc. (This should be done in an earlier lesson as a prerequisite to this lesson.) Engagement
2. Students will work in groups of 3-4 to accomplish tasks. Students will record predictions and results in their Science Logs. Ask students to hold a worm near the water in the bin. Ask the students if the worms are attracted or detracted by the great amount of water. (Concept Development) Worms cannot live in water. They will move away to avoid drowning. Worms like moist soil, but not plain water.
3. After students determine worms avoid water, instruct groups of students to build bridges over water bin. To do this lay out all the materials. Guide students to use all the materials laid out. Let students know that the cheese cloth should be dry on one side of the plywood bridge and wet on the other.
4. To begin the first experiment have students place the 2 pieces of plywood close together. A sheet of damp cheese cloth should cover one side. One side will be wet in order to attract the worms away from the dry side. Also, instruct students to place soil on wet side. (This will attract worms, too.) Teacher will monitor groups to see they have set up the experiment correctly. Any adjustments needed will be made at this time.
5. Have students place 10 redworms side-by-side on the dry side.
6. Ask students to predict what will happen next. (Worms should move toward wet side. If some fall off in water, quickly have students put them back on dry side.)
7. After all worms have moved to wet side, start experiment again. This time move the plywood pieces one inch apart.
8. Have students predict what will happen.
9. Repeat the experiment, moving one inch apart each time, until the plywood pieces are five inches apart. Have students continue to predict what will happen.
10. Have students discuss what actually happened each time the bridges were moved apart.
11. Have students make a conclusion about why the worms behaved the way they did. (Application)
12. Ask students why it is important to keep a garden area from flooding. Students will write a paragraph to discuss the benefits of worms for aeration, castings, and decomposition of waste matter. Post in hall with photographs of students conducting the experiments.
13. Use worm compost when gardening to produce better soil quality.

How do earthworms help soil?
a. They mix-up different layers of soil.
b. They add nutrients to the soil by depositing "castings" (waste products). c. They help decompose dead plant and animal material into simpler parts that can be used again by a new organism.

Helpful Hints Background: Earthworms are often called "Nature's Plowmen" because they live in the ground and tunnel their way through the ground mixing up the different layers of the soil. They eat decayed leaves and plant material. They swallow soil and little bits of animal material. Place egg shells in compost bin for calcium supply. Citrus rinds tend to decompose too slowly for consumption, but they deter some varmits. Earthworms move with 2 sets of muscles: a. circular muscles around each segment b. long muscles that run the length of the body.