A dichotomous key is an important scientific tool, used to identify different organisms, based the organism’s observable traits. Dichotomous keys consist of a series of statements with two choices in each step that will lead users to the correct identification. Background Scientists have catalogued 1.5 million species on Earth and estimate that there might be as many as 100 million more unidentified species (Giller, 2014). Classification keys are tools that provide a means to correctly identify different organisms, based on observable traits. Most such keys are created in a dichotomous format. Duration: 60 Minutes.