Yes and no. Obviously his teacher was in the wrong for yelling and screaming at him over such a trivial matter. However, in California at least, testing standards (as dictated by the state) are incredibly strict. More than one good teacher has been fired for not following the written procedures EXACTLY. Any reported deviation (state inspectors interview students and staff at random) is grounds for punishment and possible dismissal. It's a complete disaster, but this is what the teachers have to deal with. It can be incredibly stressful.
If you account for blacks who are ex-felons or on parole who can't get jobs, black people are much more likely to be unemployed than whites.
A Western study shows that black people with a criminal history are half as likely to get a return call than whites with similar history in low level positions. Further, even for blacks without a criminal history,this same study shows that they are about half as likely to get a return call than whites with the same background.
This doesn't even include the roughly 15% of the black population currently being held in U.S. prisons who may or may not eventually be released and find that no one will hire them.
Source: UC Irvine Criminology, Law & Society C7 taught by Professor Seron Spring 2010.
As a second year undergrad at a UC, I've found that the majority of the people who would appear to not have the cognitive capacity to excel in college courses were simply lacking in fundamental learning that they should have learned in high school or even middle school. All of the students I met that had trouble with calculus had trouble because of their poor algebra skills. The same is true of English classes where students had poor grammar and generally no concept of how to write a structured thesis-driven argument. Even in my upper div algorithms course, the only people who are doing poorly are the ones who did not pay attention in earlier cs classes where we already learned half of this stuff!
Clearly some people are truly incapable of excelling at these things, but I don't think that's the majority and I feel that if we could teach people better in k-12 then they would most definitely excel at higher learning schools where k-12 knowledge is expected.