Worm World Activity & Relationship to Wisconsin's Model Academic Standards for Science and Environmental Education

(adaptations for specific grade levels are outlined throughout)

Overview
Students ask questions about different habitats. Students raise earthworms to the soil surface by using a non-lethal irritant (dry mustard slurry!), then count and compare data.

Introduction
What is "good" earthworm habitat and how might we improve an area for these humble creatures? Despite their small size and inconspicuous colors, earthworms in large numbers can be a major force below ground. As mentioned above, earthworms can move a huge amount of soil each year! Also, earthworms create large pores in the soil that allow for essential aeration.

To study earthworms and their habitats, you have to find them! You can dig them up, but that destroys their habitat. Instead, you can force them to come to the surface. In this activity, adapted from NAAEE’s Worm Worlds, students use a "slurry" made of dry mustard—an irritant that bothers worms a little but doesn’t harm them—to sample earthworms. Teams count all the worms they find (both adults and juveniles) to get an idea of what might be good or bad worm habitat.

This activity can be much more than a simple counting activity. Rather, students can ask meaningful ecological questions: What environmental factors determine how many earthworms are found in different habitats? This question can be answered through further inferences, educated guesses, and observations, with the depth of the research depending on the students’ level. Some factors that may influence earthworms are the density and moisture level of the soil, the kind and type of organic matter the soil contains, whether there are transplanted trees nearby whose rootballs might have carried worms to the site, and the presence of animals that eat worms.

Materials
For each team of researchers (usually 2-3 students per team, depending upon background and age):
1. Quarter Square Meter (0.25m2) Quadrat
2. Mustard Slurry Jugs with 1 sprinkler head

• Use gallon milk jugs or watering cans
• Mustard Slurry Recipe: 2 T dry mustard powder per gallon of water. Shake vigorously. (Try Colman’s or bulk mustard from organic grocer—it must be fresh). This makes a 0.33% solution of mustard by weight. Higher concentrations might harm the worms.

3. Bowl or pan (for holding worms

4. Scissors or clippers (for clipping grass to see worms better)

5. Pencil, data sheet, and clipboard

For the whole group:
Extra jug with about ½ gallon of water (for wetting bowls and rinsing worms)

*"Standard Met" means Wisconsin’s Model Academic Standards in Science. Certainly, the activity could be expanded to include other disciplines as well.

* "Standard Met" codes in bold-face type correspond with Wisconsin’s Model Academic Standards in Environmental Education.

K-4 Pre-Activity
 

Standard Met*	Activity
B.4.1. A.4.1.	Determine which questions to ask.
A.4.3. C.4.3.	What data will help answer those questions?
B.4.1. F.4.1.	Do some background research on worms. How do they eat? What do worms eat? What eats worms? What do worms do for the soil?

4-8 Pre-activity
 

Standard Met	Activity
C.8.1.	Brainstorm questions which could be examined.
	Do background investigations on these questions in teams.
C.8.2.	Determine best method of collecting data to answer questions.

9-12 Pre-activity
 

Standard Met	Activity
	All of the above.
	Discuss Scientific Classification.

K-4, 5-8, 9-12 (ALL LEVELS)

During Activity
Break group into teams of 2-3 each

Time
Plan on spending 50-60 minutes for the outdoor investigation:

• 10 minutes to introduce the challenge and choose the habitats to compare
• 5 minutes to distribute materials and explain the sampling procedure
• 20-35 minutes for teams to set up quadrats, count worms, and complete record sheets at two spots
• 15 minutes for teams to summarize, compare, and discuss their initial findings

Site
Survey the area a few days before going out with students to determine where appropriate sampling areas might be.

 

Standard Met	Activity
A.8.2.	Standard met through entire activity.
	Gather the whole group and show them the general study area. Introduce the challenge by telling the students that there are worms here and that they’ll actually be figuring out how many and where they are.
B.4.4.	Have the students look around the area and imagine what it's like below ground in different places. List the different places and point out that all of these are potential habitat for worms.
B.4.5. B.8.5.	After they’ve named 3 or 4 habitats, have them agree on some to compare. Help them come up with a reasonable comparison, such as healthy grass versus heavily trampled grass, or bare soil in the open versus shrubs.
A.4.2.	Divide the group into teams of 2-3. Point out that since the habitats are too big to count all of the worms there, each team will take a sample or a count in a small area within each habitat.
C.4.4. A.4.2.	Show the teams how to set up their uniformly-sized sampling areas (for the younger students)—quadrats—and how to sample earthworms. Distribute materials, set a time for getting back together, then let the teams go.
A.4.2.	Allow teams to select their own sampling sites, but stress the need for all teams to follow the same procedures so that their results will be comparable.
	Circulate among the teams, helping them pick places to sample (random is best), set up their quadrats and sample worms. Things to look out for: Crooked quadrats (make sure quadrats are straight so that samples are comparable). Pouring slurry too fast (make sure all the slurry stays in the quadrat so they sample all the worms there) Injured worms (avoid unnecessary harm) Too much grass ore leaf litter on ground (remove it so they get an accurate count) No observations made of environmental factors (encourage students to fill in their entire Record Sheet) No worms (help them see that this is an interesting result and ask them to explain it based on their procedures or the habitat)
	Ask the teams to clean up and come together at the appointed time. Return worms to the quadrat or an adjacent spot (not in direct sunlight). Rinse mustard slurry jugs and let air dry. Wrap quadrat twine (or put away PVC pipe or wire hangers) and store properly.
C.4.5. C.4.6.	Have each team fill in its findings—worm numbers and environmental factors—on a chart for all to see. Then, make some calculations. For example, calculate the average number of worms (both total and just juveniles) per quarter square meter quadrat: average # worms per quadrat = total # worms from all teams divided by # of teams.
C.4.7. A.8.3. C.12.6. A.4.3. A.4.4. A.8.4.	All Have each group explain its findings, communicating the results with logical arguments.
C.8.7. C.8.9. C.8.10. F.8.2. B.8.21.	Grade 5 and up: Evaluate, explain, and defend the validity of questions, hypotheses, and conclusions. Discuss the function of a worm. Why is it shaped the way it is? Why does it move like that?
C.12.3.	Grade 9 and up: Evaluate experimental design. How could it be improved?
C.4.8. C.8.11.	Ask more questions: Which habitat had the most worms? The most juvenile worms? Why do you think this was so? In what ways did the environmental factors in the two habitats differ? Which differences do you think might explain the differences you found in worm numbers? Did each team find the same number of worms within each habitat? If not, why do you think worm numbers differed? Now that you know how to sample earthworms, the sky’s the limit for the questions you might ask about these fascinating creatures. What would you like to find out next?

K-4 During Activity
 

Standard Met	Activity
E.4.1.	Describe soil type.

9-12 During Activity
 

Standard Met	Activity
	Determine soil type.
B.8.8.	Identify microinvertebrates found.
	Identify worms using key.

 

Stardard Met	Activity
	Determine soil type.
B.8.8.	Identify microinvertebrates found
	Identify worms using key

K-4 Post- Activity
 

Standard Met	Activity
C.4.8.	More questions: Why do you think worms were there? What do you think worms need to multiply?
C.4.6.	Make a classroom chart with every group's results Drawings and reflections on activity

5-8 Post- Activity

 

Standard Met	Activity
C.8.7.
C.8.9.
C.8.10.
A.8.6.	"Lab report" on the investigation with hypotheses, questions, conclusions, graphics, and further investigations
C.8.10.
A.8.6.	Group presentations

9-12 Post- Activity
 

Standard Met	Activity
C.12.6.
A.12.3.
A.12.4.
A.12.5.	Make poster boards with background information, methods, materials, discussion, etc. What do those numbers mean? Explanation of Standard Codes