classifying is almost an instinct.When you see some one,you instantly think:'oh,wait,that guy is a nerd!' or'oh,wait,that guy is cool'.That's classifying.Maybe you don't even give it a name,but you are trying to put him in some group that fits with the characteristics that you think other people have too.
I explain myself quite badly,I know,but i hope you understood what i meant.
Classifying is done almost unconsciously,no matter if you are in HS or college,people always tend to judge and classify.
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Sick and Tired.