“Wormbeat”: A Lab to Introduce the Scientific Method
Materials:
•Earthworm
•Thermometer
•Ice
•Large pan
•Paper towel •Stopwatch
•Petri dish
Procedure:
1. Fold and moisten a paper towel with water and press it into the bottom of a petri dish. (The
wet paper towel makes it easier for the earthworm to breathe, since it has no lungs and must
breathe through its skin.)
2. Fill a pan with half full with room temperature water. Take the temp of the water (in ˚C) and
record it in Table 1 on your student worksheet.
3. Obtain an earthworm and gently rinse any soil off the animal. Place the worm in the paperlined petri dish. If your worm is too “wiggly,” lay a small piece of moist paper towel over its
head to quiet it down. Or, get a different worm from Mrs. Cooper.
4. Find the dorsal blood vessel along your worm’s back. Encourage each team member to find it.
5. Count the number of blood vessel contractions observed in 1 minute, and record in Table 1.
One team member may use his/her cell phone to act as the stop watch. (just one!)
6. Repeat step #5 two more times, giving you three trials. Record the results of each trial in Table 1.
7. Take the average of your three trials (add them up and divide by three) and record in Table 1.
8. Now add ice to the pan until you lower the water temperature to 10˚C. Allow the earthworm
to rest in its dish, on top of the ice water, 3-5minutes before proceeding to step #9.
9. Again, count the number of blood vessel contractions observed in 1 minute, and record in
Table 1. Do three trials at 10˚C.
>TIP: Make sure water temperature stays at 10˚C! Add ice if it started to warm up.
10. Return all lab supplies to the supply counter. Gently return your worm to the container!!!
11. Report your data from both temperatures to the class, and copy down all other students’ data
into data table #2. Calculate class averages.
RESULTS:
•Graph of class average data (NOT group average data)
o Be sure to give it a descriptive title
o This MUST be on graph paper, and include both X and Y axis labeled, with units,
and a key/legend if necessary!!! Be specific!