Racism and Sexism in Education

I was guilty of bigotry today in the classroom. A big athletic black kid walked into the classroom for the eighth period of the class I was substituting for. As a substitute, you learn to identify troublemakers and this boy fit the stereotype to a T. The children I have the most discipline problems with in the classroom are usually black, male, athletic or all three. At first he did nothing to allay my suspicions, talking and laughing fairly loudly. However, when class started, I forgot all about him. I got so tied up dealing with the other students that I didn't notice him, which is a good thing. (at least from my standpoint since I don't know what his grades are like) Toward the end of class I realized how well behaved he had been and was a little surprised. I even commended him on it. Of course, it could easily have been a fluke, and the kid could be a perfect monster.
The situation does illuminate certain things that have been said to me in the past and an opportunity that exists for me. People expect young black men to be irresponsible, disrespectful, and dumb. Any black male who is responsible, respectful, or intelligent is a rare find. I understand now why people have congratulated me for (apparently anyway) being all three. In fact, I am told the Army still operates according to a de facto quota system so I can expect to move up since my superiors will be desperately searching for qualified black men to fill positions. It is a little awkward but I intend to take advantage of it. I could be ashamed I gained advantage due to my race, but children of wealthy family gain advantage due to their social standing, so why not me? Oh well, whatever, race is always awkward for me to deal with.