[dichotomous tree]
[What is the Key to Classification?]
[What is a key?] * [How to make a key] * [What are these things?]
[Construct your own] * [Teacher Resource] * [Links] * [Home]


What Is A Key?

Dichotomous keys are designed to assist people with the identification of all types of living things from plants to microbes.

The word dichotomous comes from dichotomy meaning branching, contrasting or opposite ideas. A dichotomous key gives you a series of steps with a set of choices which are opposite or contrasting in nature that are initially very general and become more specific as one proceeds through the steps. By analyzing the physical characteristics of the object/organism in question and using the steps and choices given in the key, the observer can identify an object/organism based upon established traits.

You will learn all about dichotomous keys as you work through these exercises:

  1. How to make a key
    There aer some basics rules for making a key. Learn about the rules as you identify four common insects - a ladybug, a housefly, a dragonfly and a grasshopper.

  2. What are these things?
    The Chesapeake Bay is home for some 2,700 species of plants and animals. Many of these are microscropic organisms. Learn how to identify several organisms from the Baltimore Inner Harbor (a very useful skill that will help you with the Biofilms & Biodiversity activities).

  3. Construct your own
    Use what you have learned to make your own dichotomous keys.