Watching students return to school last week was strange: I felt conflicted about not joining them. A year ago, in a second-grade classroom in Prince George's County, I began what I thought would be a career in teaching. But by the end of the year my idealism was stripped away, and I knew I had to stop, at least for now. The decision has been wrenching--as difficult as my year in the classroom.

I didn't always want to be a teacher. I was a law student at Georgetown when, at the start of my second year, I read Jonathan Kozol's book "Savage Inequalities," in which he described several urban school systems and how they were failing their students. I was struck by Kozol's descriptions of life for students who live in low-income areas, and I knew I wanted to help. My motivation was fueled partly, I'll admit, by a naive sense that I wanted to save the world, but I also believed I could make things better for at least a few children. I eventually left law school, and after a one-year graduate education program, I was hired at Hyattsville Elementary School.

My conflicting feelings of relief and failure sometimes move me to tears. My first year was so emotionally draining that I am glad I've moved on. But explaining why I left isn't easy. I had seen teaching as a way of liberating students' minds so that they believed they could be or do whatever they wanted. During my short tenure, there were moments when I accomplished this, but more often I was frustrated and unable to help my students, because their problems were so vast and the school's resources so inadequate.

One day stands out--the day five of my students were suspended. It started when a boy called a girl an obscene name. She asked four boys to beat him up. They held him down on the playground and punched and kicked him while other students looked on. None of the nearby teachers saw exactly what happened; their stories reminded me of the ones you hear from accident victims--they didn't quite match up. But the girl and the four boys were referred for disciplinary action, and I agreed to it. It was late spring, and by then I was fed up with the kind of behavior I had seen every day. I was desperate and grasping at straws. The next day, all five children started a two-day, in-school suspension--meaning they were taken from my classroom and put into other classes. After that, the four boys were suspended out of school for a third day.

I am ashamed to admit I was relieved--partly because I felt they had gotten what they deserved, but mostly because it meant they were out of my class at least for a short while. They were five of my most difficult students. I could say something more politically correct: that they were my most challenging students, maybe. But they made my life, their classmates' lives and their own lives difficult. So the first day without them was terrific. The room was quiet, and the other students seemed more productive and happy.

But something squeezed my heart a little that day. In the cafeteria, my students and I saw one of the suspended students. He started crying and couldn't stop--maybe because some of the others were teasing him, or because he was ashamed of what he had done, or because he felt ostracized. Maybe he thought he had disappointed me, or maybe he didn't think at all, but he seemed to know he no longer belonged. He had had a hard time in my class. He had a reading disability, and he was frustrated all the time and often angry. Once, he told me that he would get a feeling in his chest and know he was going to hit someone but didn't know how to stop.

My relief was short-lived, because the punishment strongly contradicted my views about discipline: I firmly believe it is not the best way to get kids to learn and to want to behave. To them, suspension said that they're bad kids. And when they came back they had taken that label to heart. When one of the boys returned to the class at the end of the first day to get his coat and book bag, he screamed, "Don't look at me!" Another boy was not even allowed back that day, because the teacher in whose class he had been put thought he wasn't showing enough remorse. The girl shouted "Leave me alone!" when anyone tried to talk with her.

As I drove home that day, I couldn't help thinking that we were priming these students for prison. It was frightening to think about, and it worried me. It isn't that I had lost hope in them. I just came to realize that their situation seemed hopeless whether I had hope for them or not.

There were other incidents that troubled me. I was particularly concerned about a student who clearly needed help but wasn't getting it. At 7, he was very bright but obsessed with violent video games. In his writing notebook, I found an entry about how much he hated his parents and wished they were dead. But his mother was concerned about how it might look if he were sent to a school counselor, and the counselor thought it was a matter for his parents to deal with. I couldn't give him the help he needed while attending to my 27 other students.

So when people ask me why I am not teaching this year, I tell them that I spent too much time as a disciplinarian and not enough time teaching. I didn't know how to change the things that were happening in my classroom, and I didn't know how to cope with the feeling that I wasn't in control.

I'm left with this: I walked away from teaching because I was tired of feeling as if I was alone in battle. Because I was tired of trying to make parents see that their children needed help. Because I was tired of scrambling to get help when none was available. And because I was tired of leaving school every day feeling as though I had failed my students. Recently, a friend told me I was arrogant to think I could do so much as a teacher. It wasn't that I wanted to do so much; it was that I never dreamed there would be so much I couldn't do.

Natalie Chamberlain Reis is working as a legal secretary for a Washington law firm.