Activity: Finding Nature's Order: Classification

Objectives:

This lesson is designed for students to learn to recognize and understand the relationships between living organisms. Students will determine that related organisms have a common ancestor and/or common traits.

Age Level:

Grades 6 - 12

Materials:

• Shells, fossils, or other items that are similar to each other, but not identical.
• Paper
• Markers/pencils
• Rulers

Time:

Allow for 10-20 minutes for an introduction to the topic including new vocabulary (see below), and 30 minutes to complete the project.

Background:

Scientists have identified 1.8 million species living today. Some researchers estimate that there might be as many as 100 million! However, those species alive today are only a very small percentage of the perhaps billions of species that have lived on this Earth since life first evolved approximately four billion years ago.

Over 75% of the described living species belong to the Phylum Arthropoda, which includes such diverse organisms as lobsters, barnacles, spiders, and insects. The insects are by far the most abundant arthropods. MollusksMollusk:
A member of the phylum Mollusca; also spelled mollusc (most especially in the United Kingdom). are the most species rich group in the sea, and bivalves comprise the second largest class of mollusks. How are the many species of insects or bivalves arranged, categorized, and classified? How does the classification scheme reflect phylogenetic (evolutionary) relationships? It can be a bewildering yet extremely interesting problem. The following activity is intended to demonstrate the importance of classification through the examination of objects and the identification of common characteristics that organisms do or do not share and the way in which subgroups are created.

Procedure:

Part I — Discussion

1. Introduce new vocabulary to your class and provide definitions (e.g., classification [Kingdom Phylum Class Order Family Genus Species], phylogeny, taxonomy), as appropriate to the grade level.
2. Facilitate class discussion on the importance and relevance of classification and determination of the relationships among living organisms. Optional Extension: Introduction of Carolus Linnaeus as inventor of modern classification (1758, Systema Naturae). Linnaeus developed binomial nomenclatureBinomial Nomenclature:
   The two-part scientific name — genus and species — for a plant or animal. to identify organisms by a generic (genus) and specific (species) title.

Part II — The Project

1. Divide students into groups of 3 or 4. Distribute approximately 25-30 shells (or other objects) to each group. (If you only have a few examples, conduct the project as a full-class activity.)
2. Provide rulers to students and ask them to think about ways in which objects are similar or different (size, shape, function, appearance etc.).
3. Ask students to separate the objects based on their physical characteristics according to what they think is most important (size, shape, function, appearance, etc.).
4. Move between groups, asking thought-provoking questions about why students chose to separate objects in the manner that they did. Did they separate the shells by size, and can they be further divided by shape? If they were separated first by appearance, can they be further subdivided by color?
5. After each group has subdivided their objects into groups, ask them to write a brief description of their classification scheme by: (a) describing the rules they followed to create their relationships; and (b) describing why they chose their classification scheme. Have a representative from each group make an oral presentation to the entire class following the activity.

Helpful Analogy for Struggling Students:

As an example, think of your Halloween candy. On Halloween night, after returning from trick or treating, what do you and your friends do? Many kids pour their candy out on the floor or bed, and separate the candy into piles based on how the candy items are the same, and how they are different. The chocolate goes into one pile, the Smarties™ into another, the Sugar Daddy™ into yet another pile, until all the candies are in the appropriate places. Biologists do the same thing with life forms (see also KidsBiology.com Classification of Living Things).

See also the Taxonomy Activity.