Teachers get very excited about the prospect of dissection with students. It's a hands-on approach to teaching anatomy and an activity we would expect the students to be excited about jumping into.....so why did our first attempt seem to be a bit of a let-down?
When we look at a fabricated textbook style diagram of an earthworm, the picture consists of bright colors, and neat arrows points out various parts of the anatomy. Very neat (and odorless.)
The reality of dissection is different in every way, though, it is not the bloody mess that one may imagine. The earthworm used in our dissection lesson did not come out of the backyard, it had been preserved for dissecting and was part of a kit of various specimens.
The external body was examined to determine the location of the anterior and posterior ends and the dorsal and ventral surfaces. The worm was pinned to the tray with the dorsal side up and prepared for cutting.
Nervously, the student cut the worm as instructed and pulled the skin back for internal observation. At first sight, it looked dry and dirty. Parts were not as easy to identify as they appeared in the neat, colorful textbook diagram. After placing the specimen under a dissecting scope (also known as a stereo microscope) the students were able to locate and identify some parts of the anatomy.
The activity provided the students an opportunity to observe firsthand the internal parts of an organism. Overall, they expressed no disappointment, however, their final comments were: "Can we do something bigger next time?"
Tips for a successful dissection:
- Prepare in advance by learning about the systems of the body, particularly, the circulatory, digestive, nervous, reproductive, skeletal and muscular.
- Give the students an idea of what to expect.
- Have plenty of rubber gloves available.
- A high power magnifying glass or dissecting scope are helpful when the specimen is small.
- Stay engaged with the students and guide them through the steps.
If you attempt a dissection with your students I wish you a successful and fun lesson.
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