Yes or no… that was the question of the afternoon. We set up a dichotomous key to identify any Heron by asking them a series of yes/no questions. The first question was "Is the person a 4th grader?" This helped us eliminate half the class. We continued to develop questions that would eliminate half the group that was left to sort through. Eventually, we were left with one person – our identification key had worked.
Later this week, we'll use a dichotomous key to identify trees. There are also keys for lichen, rocks, wildflowers…it works for anything.
The logic used to develop them is wonderful, too. Can you identify a trait that half the group shares? Is it an objective trait or subjective? One child suggested, "Do they have weird shoes?" The Herons realized that "weird" was not a useful descriptive word since it was an opinion. We also talked about how our key would only be good today since it involved clothing stripes and other things that would be different tomorrow.
A great challenge is to determine what the fewest number of questions a given group would need to get down to a single individual.
The Rookery 
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