On the day after Martin Luther King Jr. was murdered in April 1968, Jane Elliott's third graders from the small, all-white town of Riceville, Iowa, came to class confused and upset. They recently had made King their "Hero of the Month," and they couldn't understand why someone would kill him. So Elliott decided to teach her class a daring lesson in the meaning of discrimination. She wanted to show her pupils what discrimination feels like, and what it can do to people. Elliott divided her class by eye color -- those with blue eyes and those with brown. On the first day, the blue-eyed children were told they were smarter, nicer, neater, and better than those with brown eyes. Throughout the day, Elliott praised them and allowed them privileges such as a taking a longer recess and being first in the lunch line. In contrast, the brown-eyed children had to wear collars around their necks and their behavior and performance were criticized and ridiculed by Elliott. On the second day, the roles were reversed and the blue-eyed children were made to feel inferior while the brown eyes were designated the dominant group. What happened over the course of the unique two-day exercise astonished both students and teacher. On both days, children who were designated as inferior took on the look and behavior of genuinely inferior students, performing poorly on tests and other work. In contrast, the "superior" students -- students who had been sweet and tolerant before the exercise -- became mean-spirited and seemed to like discriminating against the "inferior" group. "I watched what had been marvelous, cooperative, wonderful, thoughtful children turn into nasty, vicious, discriminating little third-graders in a space of fifteen minutes," says Elliott. She says she realized then that she had "created a microcosm of society in a third-grade classroom." Elliott repeated the exercise with her new classes in the following year. The third time, in 1970, cameras were present. Fourteen years later, FRONTLINE's "A Class Divided" chronicled a mini-reunion of that 1970 third-grade class. As young adults, Elliott's former students watch themselves on film and talk about the impact Elliott's lesson in bigotry has had on their lives and attitudes. It is Jane Elliott's first chance to find out how much of her lesson her students had retained. "Nobody likes to be looked down upon. Nobody likes to be hated, teased or discriminated against," says Verla, one of the former students. Another, Sandra, tells Elliott: "You hear these people talking about different people and how they'd like to have them out of the country. And sometimes I just wish I had that collar in my pocket. I could whip it out and put it on and say 'Wear this, and put yourself in their place.' I wish they would go through what I went through, you know." In the last part of "A Class Divided," FRONTLINE's cameras follow Jane Elliott as she takes her exercise to employees of the Iowa prison system. During a daylong workshop in human relations she teaches the same lesson to the adults. Their reactions to the blue-eye, brown-eye exercise are similar to those of the children. "After you do this exercise, when the debriefing starts, when the pain is over and they're all back together, you find out how society could be if we really believed all this stuff that we preach, if we really acted that way, you could feel as good about one another as those kids feel about one another after this exercise is over. You create instant cousins," says Elliott. "The kids said over and over, 'We're kind of like a family now.' They found out how to hurt one another and they found out how it feels to be hurt in that way and they refuse to hurt one another in that way again."