"It was really hard on him. He didn't want to go against . . . his troops. It cut him in half, but he said he could not stand the atrocities that he had stumbled upon. He said he kept thinking, 'What if that was my mom, my grandmother, my brother or my wife?' " -- Margaret Blank, mother of Army Spec. Joseph M. Darby, interviewed May 6 by ABC News.

To Nader Twal, the way Joseph Darby talked himself into exposing that Americans had abused some detainees at Iraq's Abu Ghraib prison was a classic lesson in what Twal is trying to teach his English and philosophy students: the ability to make a principled decision.

The soldier saw behavior he believed was wrong. He personalized it and listened to his conscience, whatever the cost, said Twal, who uses literature, debate and role-playing to teach ethics at a special academy inside Millikan High School in Long Beach, Calif. Twal's students discuss issues ranging from the rules of war to the themes of injustice in such novels as "To Kill a Mockingbird."

"Conscience is like a muscle," Twal said. "We either practice it and it grows, or it atrophies. What I do in my classroom is to give students an opportunity to exercise their conscience. I want to develop character, not self-esteem. . . . I think the greatest disservice that we have done to our kids is to tell them they are okay the way they are."

Such teachings are not standard curriculum for a public school. In an era when test scores for core academic subjects such as math and reading are paramount, some educators say they have no time to teach character education -- and to some parents, it is best left in the home.

There are teachers, too, who say that in today's litigious society, they are afraid to insist that students adhere to rules of right and wrong.

Yet character education is gaining new strength across the country, as society grapples with questions about how ethically grounded young people are and what role schools should play in dealing with the issue. "Schools have to do this," said Sherrie Hart, a high school teacher in Fayetteville, N.C., and a former state character education teacher of the year.

"It can reinforce what many children learn at home," she said. "But there are a lot of students who don't have the support at home and don't have the moral education. A lot of schools say they don't want to do it, but where are the kids going to get it?"

Character education is a subject whose time has come and gone and come back again under different names and approaches.

In the 1960s, as the Vietnam War and civil rights struggles fueled students' political activism, "all hell broke loose," said Francis Ryan, director of American studies at La Salle University in Philadelphia. As a result of this questioning of authority and increasing cultural diversity, many educators became reluctant to pronounce what behavior was right or wrong, Ryan said.

Today, character education has reemerged, with debates raging among philosophers, psychologists and others about the nature of conscience and ethics.

Many schools have dipped in, with some states requiring character education. But there is no consistency to the requirements. Virginia mandates it in all schools, though the state doesn't mandate an approach; Maryland high school students must perform 75 hours of community service (which some ethicists say should be graded so students would take it seriously). D.C. schools don't have a systemwide requirement.

In some schools, students are exposed only to lectures about ethical behavior, lessons not apt to sink in, teachers and students say. Effectiveness requires a comprehensive approach, they say, incorporating all phases of school life, with connections that students of all ages can personalize and practice.

"If a teacher just touches upon the subject, it is going to take no effect," said Ryan Owen, 18, a senior at the PEACE Academy in Long Beach, south of Los Angeles. "What works is when we have interactive learning."

Principal Sheila Ford, of Mann Elementary School in the District, has adopted a comprehensive approach with a program called CARES, which stands for cooperation, assertiveness, responsibility, empathy and self-control.

The aim, she said, is to "build a community that cares." Teachers hold morning meetings with students to discuss issues, and kids routinely address them through art, music and drama. Posters display not only particular virtues, such as empathy, but also examples of such behavior.

And Ford talks to students about applying what they learn to their lives. "I spoke to fifth-graders about how it feels to tell someone you aren't going to be their boyfriend or girlfriend anymore," she said. "We talk about real issues all the time."

Arthur Caplan, director of the Center for Bioethics at the University of Pennsylvania, said most efforts to teach character education are inadequate, in part because of politics.

"Some people want ethics taught, but only if it is going to stay off of certain subjects, like sex and drugs, which are probably for most young people the few areas where they can make moral choices," he said. "And other people don't want it because they are afraid of being prudish or too conservative. And that's a mistake."

Another key ingredient to success is the notion that everybody in the school has to be a role model displaying ethical behavior for students to internalize its importance, students say.

"Somebody can be a really great teacher, but if no one else ever mentions ethics, if it is . . . not reinforced by role models and undercut, in fact, by your boss or your commander . . . then you might as well not bother because the culture you live in sets the ethical tone as much as any teachings," Caplan said.

Ryan said that today's "me-centered lifestyles" must be defused to "nurture the components of a moral system."

One way to do that, said Bill Shore, author of the book "The Light of Conscience," is for students of all ages to be taught about people in history whose acts of conscience have somehow improved a part of the world, so they can see that acting ethically can change their own world.

"They should be told: 'You should live as if the world is perfectly balanced between good or evil, and anything you can do can tip it either way,' " he said.

Twal, who teaches at the PEACE Academy (which stands for "personal success through empowerment, academic achievement, conflict resolution and ethics in action), said a key is to personalize issues.

For PEACE senior Becca Anderson, 17, a debate on how to behave in war taught her about human dignity. She was asked, she said, to imagine being on a battlefield and having to decide what to do when finding a wounded enemy combatant, and then being the wounded soldier.

Darby, she said, is one of her heroes.

Mann Elementary in the District gives its students -- such as Annie Spaller, center, and Anna Fishbein, right -- character education.