As an example, here's Tom Berenger in The Substitute:
That was from the nineties. Notice the chalk, the music, the ability to spot an ice pick in the student at the back. Clearly, a military background was required. But, if you didn't have a military background, there an attitude and a Harley would get you through al'la Jim Belushi in The Principle:
As you can see, reaching out to troubled blacks and hispanics is important in these films. That's the message being imparted. White folk are okay to help if they're there, but the kind of white people here are scum, and really, anyway, everyone knows good whites go to nice schools and its only through a sense of social responsibility that they go to the underfunded crime ridden schools of those who aren't white. Why, just take this scene from Dangerous Minds:
You got to rage against the dying light, right?
The more I thought about it, the more I realised just how much there is a certain cliche to the troubled teenagers of the school film. Outside the fact that all look like they've been repeating the final year of school for years (which probably explains their angst), you could pretty much swap their lines from each one of these movies and find no real difference in any of them. In fact, I'd probably argue that only the Coolio hit from Dangerous Minds lets you remember the kids differently. You may think are different, but a film like One Eight Seven--
--shows you that you cannot.