Big Idea: All cultures have developed names for the living things found in their environments. When various everyday names are used for the same organism, confusion is possible. So, scientists have developed an international system for naming and classifying all organisms. Identification guides, called keys, have been developed to help all peoples recognize and identify organisms according to their scientific names.
Classification keys are usually dichotomous in arrangement. The word dichotomous comes from the word dichotomy, meaning “two opposite parts or categories.” A dichotomous key gives the reader a series of opposing descriptions of basic features of an organism. The reader studies the specimen and selects the descriptions that apply until reaching a statement that characterizes only one species of organism, and thus has identified it.
Task: In the first part of this investigation students will practice using a couple of typical dichotomous keys to identify the genus and species of several different leaves and salamanders. Then, as a lab group they will create your own dichotomous key to categorize a diverse group of lab instruments. Lastly as an individual students will create a dichotomous key that can be used to classify microscopic cells to kingdom.