Forget what I said here.
I'm still a good teacher. I have a student who is currently in foster care and wants to make a way out for herself. She told me that when she started in my class she wanted to do that. She sits away from the troublemakers, takes notes of what I show them how to do, and does her homework. Surprise, surprise, she gets all of the questions right when we take a post-assessment over the chapter.
My failure in teaching is reaching the troublemakers. I just can't seem to do it. There's no simple formula. It's not a lack of parenting; my exemplary student has no one driving her and she motivates herself.
One of the things I notice is that I cannot penetrate the culture in which some of my students live. Fighting is their favorite topic of conversation. They have pit bulls that they fight against other dogs and they think it's okay. Some of my students are so careless about life that they fully expect to be dead before they have the opportunity to graduate from high school. What kind of carrot do you dangle in front of those kids? Some of my students think that their chances of being professional athletes are better than even. I did a demonstration the other day with flipping two coins and comparing that probability of getting two heads as a result with shooting dice (Craps in official venues) and even after the students flipping the coins lost hundreds of simulated dollars, they still insisted that they "always win with dice." There is simply no sense of reality that I can impose on their world views.
Increasingly I teach in a world where emotion and pride dominate logic, reason, and compassion for others. The slightest insult can escalate into violence in an instant. At the high school level, any fight participants are taken away in handcuffs and arrested, and yet there is no stigma attached. It's simply the way business is done here.
I can't imagine ever being put in handcuffs, and maybe that's my problem.