Learning from once-alive organisms

Teaching Pre K-8, Apr 1997 by Kathleen Vitale

A unit you can use to give your students a first lesson in anatomy

Most kids love to take things apart in an attempt to understand their inner workings. To dissect means "to cut apart," and that's just what you can do in your classroom with once-alive things. There's nothing like dissection to pique children's interest in natural science. Dissection can fit into the elementary science curriculum in various ways. You can incorporate it into botany or biology units. It works well from third grade (flowers can be successfully dissected) through sixth grade. Also, whatever the grade level, it's an easy unit to prepare.

All due respect. Begin the unit with a statement about respecting life forms. My students were very respectful of the creatures we were cutting into, viewing them as onceliving organisms that were now helping us understand other living things.

Next, ask what kinds of people use dissection in their professions (e.g., Michelangelo, who dissected dead bodies in order to understand musculature for sculpting, and geologists, who dissect the earth itself when they take core samples).

Encourage kids to start with a thorough external examination of the organism before cutting. This is called gross anatomy - the study of what can be seen with the naked eye. Ask them to point to various parts of their organism that are labeled on any diagrams they may have. The coloring books cited toward the end of this article have many easy-to-follow diagrams.

Some of the readily available things students can dissect in the classroom include clam worms, sea creatures, flowers and parts of cows, lambs or pigs. Clam worms, which can be ordered from science supply catalogs, are simple creatures that are good for studying gross anatomy (appendages, mouth parts and body segments).

Supermarkets are great places to get other easily dissected creatures. Squid is a relatively simple organism, but you can distinguish some interesting parts, such as the "pen," a stiff piece of cartilage that looks just like a quill pen, and the ink sac. Squid also have a siphon tube used for jet propulsion. All these parts are easily seen by amateur dissectionists, including the teacher! Shellfish are also good for dissecting. Other supermarket treasures:

bones (cow legs and knuckles) - ask the butcher to saw them lengthwise for a cross-section of marrow; spongy, compact bone; and blood vessels eyes and hearts - cow eyes are large and interesting to dissect, and so are cow, pig and lamb hearts. Call around and mention that this is a school project and you may get the parts for free.

fish - they have many organs that are easy to identify. Try to find a fisherman willing to donate fish. Keep them in the freezer until you have enough for groups of three students.

flowers - they're often obtained without charge, either from your garden or by asking a florist. Our local florist regularly donates gladiolas. These are great flowers for dissecting because each stalk has many blooms. Each student can then have his or her own.

Easy does it. Caution students to go slowly when they actually begin cutting so that they don't accidentally cut into organs. They should be cutting through layers of connective tissue (skin and muscle) to get down to the organ systems.

You can have students draw what they see inside the organism or do more research about the organism - perhaps to identify parts that weren't identified during the lesson. A drawing aid could be a blank outline of the organism to be dissected.

Relate the creature or part to be dissected with the unit you are studying and ask students to generalize from the organism they dissected to other familiar organisms. For example, we can see organs in fish that we have in our bodies. Help your students draw parallels between seemingly unrelated organisms so they can delve more deeply into areas of science where such subtle relationships are very important.

Since not all children are going to be excited about cutting into once-living things, have a team of students divide up the work. One can cut, others can draw and they'll all benefit from seeing up close the inner workings of the organism.

References. It helps to have a reference as to what parts are what. Don't hesitate to cut open an organism at home before you introduce the lesson to the class.

I've found the Botany Coloring Book, Marine Biology Book and Zoology Coloring Book (all published by HarperCollins) to be extremely helpful. They give clear drawings with labels of many organisms. You can use the drawings to help students go from diagram to the real thing. Later, the children can color in the identified parts.

For the dissection of mammal parts as an aid for studying the human body, the book Blood and Guts by Linda Allison (Little, Brown, 1976) is excellent. It has detailed, easy-to-follow drawings and instructions for dissecting organs using supermarket items.

I think you'll be energized by the motivation this activity creates. It's always worth the effort when you have kids who are really excited about a lesson. Dissecting once-alive organisms is an effective way to bring the science text to life.