If America is the land of equal opportunity, then teachers are the equalizers. We are the last hope for those kids that come from environments with very little hope to begin with. Yet, if we try to focus on them, we tend not only to see little result and we also neglect who used to be the good kids, because in the end, you can't change anyone; you can only hope to indirectly inspire them to change themselves.
Kids come from incredibly unequal situations. What kinds of situations they come from, I believe, is irrelevant beyond saying that some are good and some are bad. But we, as teachers, have the responsibility to provide all of them with as much opportunity for present and future success as we can. I can't speak for other teachers, but I know that in myself I tend to want to disregard the bad kids, feeling powerless to help them if they're not going to help themselves. However, just because you think you can't, doesn't mean you shouldn't try. (Coincidentally, these 'bad' kids I'm referring to are often the ones to whom you say, "Just because you can, doesn't mean you should.") In many situations we might be the last hope for these troubled youth, which makes it very much our responsibility to still try.
However, to attempt to help troubled youth does not mean you should focus on them. This seems to not only be counterproductive for the bad kids, but it tends to alienate the good ones as well. I was one of the 'good' kids growing up. I was fairly intelligent and well-behaved (except in Spanish class). Nevertheless, too many times I felt like I was on the brink of becoming a bad student, and having leaders and teachers ignore me was not helping. Then came a scout leader that actually noticed me. The remarkable thing was, he noticed everyone. He didn't seem to have a 'bad kid' radar. He simply gave every scout his fair share of unique attention, and he had a positive influence on everyone for it. This is what I want to do as a teacher: give every student his/her fair share of unique attention. I say unique attention because you have to show that you actually know who they are, so your attention doesn't feel meaningless. And that's as deep as I'll go about it.
I've hinted very strongly about the third point already, which is how to actually try to effect change. It starts with simply knowing them and giving them proper attention. Yet still, even when a student admires you, he might still have incredible difficulty behaving himself, or turning in even the easiest assignments. No matter how many times you remind him, or how much you try to make the assignment as fool-proof as possible, he still can't seem to do it. You can have serious talks, send him to the office or counselor, create a personalized education plan, but nothing seems to work because in the end, he has to suddenly realize that it's in his best interests to do what you ask. And you can't just give up on him. That's what he'll expect you to do. And it is tempting. He is constantly disruptive and disrespectful, holding up the entire class. The answer? I think it's as simple as sticking with it and mixing it up. There's no golden answer to even a single student's issues, because as I said, it's inside him. So if you just stick with it, and mix it up, the hope is that eventually, somehow, something you said at the most inconsequential moment might spark a flame in his brain. Suddenly it makes sense. Suddenly he is motivated to make changes, no matter how small and unnoticeable they may appear.
And finally, one of the most difficult and important things to do is not turn the 'bad' kids into enemies. They don't have to be your friends, but they need to know you don't abhor their presence (even though sometimes, let's be honest, you do). Because if and when it suddenly dawns on these kids that they need to get their act together, it will be someone they looked up to that somehow, however inadvertently, found the light switch in their brains and turned it on.
And I've ranted and soap-boxed long enough. I'm writing this for myself. These are things I need to do better as a teacher, to do my job and attempt to provide every student with the opportunities he/she deserves.