Classification

Science Scope cover, February 2009In last month’s issue of Science and Children, Bill Robertson asks the question “Why do we classify things in science?” He notes that many teachers teach classification as an end in itself or as a communications exercise. He suggests that “Classification in the classroom should lead toward the understanding of concepts, or at least should be done with an eye toward the ultimate purpose, such as the classification of rocks leading toward an understanding of the formation of geologic features” (page 70).
I visited an elementary class in which the teacher had a collection of small objects, which the students were to categorize. The students had lively discussions as they sorted the objects into the compartments of a cafeteria tray. But the teacher went beyond this simple activity – she had the teams exchange trays and try to figure out what characteristics the other team used to create the groups. Then she gave them some new objects and asked where (and if) the objects fit and whether the groups should be changed or expanded to accommodate the new objects. Two of the articles in this Science Scope also take classification one step further, with follow-ups to scavenger hunts using GPS units and digital cameras!
There are many terrific websites that help students understand the concepts of biological classification, such as those in the Explore Classification section of SciLinks. But let’s not forget that other sciences also use classifications such as the the Periodic Table, simple machines, galaxies, and hurricanes.
Regardless of the subject, instructing students in the process of identifying similarities and differences (through the processes of comparing and classifying) has been found to improve student achievement. In Classroom Instruction That Works. Robert Marzano and his colleagues cite this research and describe two types of classification activities: 1) giving students the categories and asking them to classify items and 2) giving students the items and asking them to sort them into categories of their own creation. The authors note that using graphic organizers can help students to determine the patterns. And science is full of graphic representations of classifications schemes (just think of what can be learned from looking at the Periodic Table). History of Life: Looking at the Pattern depicts the current thinking about how living things are classified based on patterns and observations.
How many of us learned that Pluto was classified as a planet and that there are three kingdoms of living things? It’s exciting to see how new information causes us to rethink what we thought we knew.

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