A dichotomous key is a classification tool that identifies everything from organisms to objects based on observable traits.

If you’re wondering how to make a dichotomous key, begin by taking stock of the objects, different species of animals, or plants that you’re trying to identify. Then, compile a list of their features and qualities. You’ll use these physical characteristics to divide, and then subdivide, the subjects that you’re identifying until you reach your final assessment.

Dichotomous keys tend to resemble a flow chart, with one primary characteristic at the top branching into more specific traits or questions. Worried about nailing down the format? Download FigJam’s free dichotomous key templates and easily customize them for your ID needs.

Students, scientists, and teams of all kinds use dichotomous keys to organize information through identification steps and solve everyday mysteries. With a streamlined format that flows from big picture to fine print, dichotomous keys make it easier to get a handle on unknowns—catalyzing broad connections and closer looks.

To learn how to read a dichotomous key, it may be helpful to first consider why it is called a dichotomous key in the first place. “Dichotomous” can feel like a bit of a mouthful, but it’s also instructive—it translates to “including exactly two choices”—and relates to how the chart unfolds.

So when using a dichotomous key, what do we look at? Start at the top, where you’ll find your primary characteristic—in our case, “Dog.” From there, you’ll encounter two choices—yes or no—which will lead you one step further into your analysis. For example, “Does the dog have curly hair” (yes) will lead to another yes/no question, like “Is the curly hair black or brown?”

Eventually, as you work your way down the dichotomous key, you’ll land on the identity of your dog. (Curly-Coated Retriever, btw.)