Six decades later, the Holocaust remains a painful and emotionally draining topic -- and a special challenge for middle school and high school teachers who have to instruct students about one of the most horrific episodes in human history.

Despite its importance, Holocaust scholarship is just beginning to work its way into history lessons in much of the country, and teachers volunteering to tackle the subject often find themselves developing courses from scratch, without much formal training.

"My own education about the Holocaust was not close to what I am providing today in my classroom," said Kimberly Watkin, a history teacher in South Burlington, Vt., who offered her high school's first full-term course on the Holocaust this past school year.

To become better versed in her subject matter, Watkin recently joined about 30 other educators from Croatia, Lithuania, Poland and 11 states at a five-day program on the Holocaust at Columbia University.

It was sponsored by the Jewish Foundation for the Righteous, which in 2000 began to bring schoolteachers from across the country to seminars with top historians in a campaign to improve teaching about the Holocaust.

"More often than not, you'll find that students are introduced to the Holocaust by an English teacher who wants them to read Anne Frank's diary," said the foundation's executive vice president, Stanlee J. Stahl. "We did this because we discovered that teachers did not know the history."

The foundation was established in 1986, and its primary mission is to provide financial aid to non-Jews who risked arrest and execution to rescue Jews during World War II. It helps about 1,500 surviving rescuers around the globe.

But this month, it offered lectures for teachers on the development of the Nazi regime, refugee policies, life under German occupation, the role of industry in the Holocaust, the efforts of rescuers and the machinery of the system that killed 6 million Jews.

As in the past, many of the participants came from schools in towns where there are few Jews and where the Holocaust is generally taught in just a few days as part of a larger U.S. or world history course or as part of a literature program.

In one seminar, Robert Jan van Pelt, a professor at the University of Waterloo in Ontario and the author of several books on concentration camps, posed this question: Why did the death camps use gas for mass murder?

"Shooting," he noted, "is a perfectly fine way of killing people."

Guns, in fact, were the weapon of choice when mobile death squads began large-scale massacres of Jewish families in the Soviet Union in 1941. Why switch to stationary camps and gas chambers, which were less efficient?

The answer, van Pelt suggested, may be that Nazi leaders were concerned that the relentless killing of women and children up close with a rifle would exact a psychological toll on German troops.

Gas "allowed those who took part in the operation to remain clean," he said. "The issue is not how someone could kill, but how they could continue to do it."

His point touched on an insight that many teachers came away with: Despite the mechanization of mass killing, the killers were human beings -- which makes their actions all the more shocking.

"These were people much like you and I," said Mark Johnson, a teacher at the Seattle Preparatory School. "What is it in humanity that allowed it to happen?"

U.S. colleges have only begun to offer a deeper curriculum on the Holocaust in the past 10 years, said Deborah Dwork, a professor of Holocaust studies at Clark University in Worcester, Mass. She called the delay "a polite form of denial." Six states -- New York, New Jersey, Florida, California, Illinois and Mississippi -- now mandate at least some teaching of the Holocaust in public schools.

Students "don't understand how this could have happened, and it is tough to show them, even in a nine-week course," said James Trill, a teacher at Pioneer Valley Regional High School in Northfield, Mass. "The challenge to us is reaching these students and saying, 'The people who did this are people like all of us, who have a life and have families.' "

Stanlee J. Stahl, coordinator of a Holocaust teaching seminar, left, talks with Jolanta Ambrosewicz Jacobs, a university professor from Poland.