The common wisdom is that America is doing its best to forget Vietnam. That's not entirely true.

There's this former Marine lieutenant named Philip K. Straw. He came back in 1969 from his year in combat with a Bronze Star and Purple Heart, and when he started to work in a congressman's office in 1970 he wanted to know more about the war that had almost cost him his life. He read books and articles. He haunted libraries. He watched the protest marches.

Then he went to the University of Maryland looking for a course on Vietnam. They didn't have one. Somebody said, Well, why don't you teach one yourself?

This fall the university offered "America in Vietnam 318a" in its general honors program. The teacher is Phil Straw.

"I never taught anything in my life this side of Sunday school," he says during a quiet moment in the offices of Rep. Clarence Miller (R-Ohio). "But you know, I come home from Vietnam, I'm 23, I got a ticket on history's bus and took a ride, as somebody said. I'd just been directly involved in the dominant issue of the '60s, and I had this desire to learn more. It went on from there."

He figures he is the only Vietnam combat veteran teaching a course on the war in a major university. (At a recent conference on "Vietnam and the Classroom," only one of the 11 speakers and three of the 75 teachers attending had even been in Vietnam.)

It is some course.

Last month he had retired general William Westmoreland in to talk to his 18 students.

He brought in Everett Alvarez, Fred Cherry and Everett Southwick, who were POWs as long as nine years. "They told the kids this is still the greatest country going. It gave them a whole new perspective. I tell you, it's the last time I'll ever complain about traffic on the Beltway."

Future speakers include former senator Eugene McCarthy and Lyndon Johnson's defense secretary, Clark Clifford.

The students made up a survey, "Where were you in '68?" ("How did the war affect you personally? What was your reaction to the social unrest? What would have happened if Robert Kennedy had lived? Or Martin Luther King?") Students will poll people in the community from 35 to 45 and write an essay on their findings.

Then there is the issue interview, which accounts for half the grade in the three-hour-a-week course. Straw has rounded up a remarkable gallery of people willing to talk on specific aspects of the war: David Brinkley; J. William Fulbright; Barry Goldwater; former Joint Chiefs chairman Thomas Moorer; Assistant Secretary of Defense James Webb, who wrote the shattering "Fields of Fire"; Bui Diem, former Vietnamese ambassador here; retired generals; ex-pilots; journalists; and even Col. David Lownds, who commanded the Marines at Khe Sanh.

The students, working from extensive reading and TV viewing, will ask about media coverage of the war, antiwar veterans, the Paris peace treaty and so on.

Another requirement is a visit to the Vietnam Veterans Memorial. For each student, Straw made a bookmark with the name of a casualty, say, Charles McMahon Jr., the last GI killed, or Cliff Cushman, an Olympic hurdler. He wants the students to learn about these people, so that when they find the names on the memorial it will be more real to them. So that, as they touch the memorial, it touches them.

"I want to personalize history for them," the 40-year-old Straw says. "I tell them I'm teaching the course to them but for the 58,000 who died there. They understand that. They know just enough about that period to want to know more. They pick up bits and pieces, they've seen the movies and the articles. They're really motivated."

He has 12 men, six women. Two are Vietnamese, two black, one a veteran's son. The university allowed him three more than the 15 to which honors classes are limited. There is a waiting list. One woman told him she debated with her father about the Tonkin Gulf incident, and while she was amazed at how little he knew, he was astounded at how much she knew.

"The worst thing would be if these kids were Rambo-ized," Straw adds. "I try to expose them to as wide a variety of resources as possible. I'm not proving any one point but bringing them all out. The greatest injustice people of whatever age can do to those who fought in Vietnam is to ignore them, to forget, to assume the wrong things."

He wants to make sure the students know that not all the veterans came home maladjusted or despairing. He himself sees the war as "an unfortunate national tragedy that had far-reaching effects from which we can learn valuable lessons applied to the '80s and beyond." He said he is delighted at how perceptive the students are, at how they give him what he calls "the teachable moment," when the whole group becomes so intent on what he is saying that they may remember it the rest of their lives.

Straw, who never dreamed he would wind up a teacher ("I'm a teacher who happens to be a veteran, not the other way around"), left his native Athens, Ohio, for the University of Kentucky. In 1967, working at The Louisville Courier-Journal, he decided to get some control over his military future rather than be drafted.

One lunch hour he visited all four services, picked the Marines, went to Officers Candidate School and then the Naval Justice School and communications school. Naturally he was assigned to a rifle platoon.

November 1968: Fresh from the States, Straw found himself fighting along the DMZ near Con Thien with the 3d Marines.

"We were coming into a cold landing zone, not taking any fire," he recalls. "We had to secure a third of the landing zone perimeter. It was a beautiful day, warm and sunny, very humid, a great day for a picnic. Then we came under intense artillery fire -- I think they saw the choppers landing; the fire seemed to be from across the DMZ -- and we got hit pretty good. Total confusion. I had nine men wounded, one dead.

"I was on top of the hill when we started getting hit. I gathered up two or three of my marines with me and we proceeded to go down to the perimeter line about 25 yards away."

The citation for Bronze Star with Combat "V" reads: "Second Lt. Straw rushed to the area where the rockets were impacting and carried a wounded Marine to the relative safety of a bomb crater and returned to the hazardous zone on five subsequent occasions, evacuating casualties. Skillfully directing his men in the accomplishment of their mission, he then carried each of the six injured men to the medical evacuation helicopters . . ."

He doesn't talk about it much. He keeps the medal in a trunk in the basement.

"It was pretty intense. It could have lasted as little as 20 minutes, but it's a lifetime when you're doing it. I just reacted as anybody else would. I was hit, but not bad enough to medevac. Just bad enough to, let's say, make an impression on me."

He had been in Vietnam 11 days.

Straw lives in College Park with his wife, a doctoral candidate, and their two children. He feels a special closeness to his students, who are "around 20 years old, the same age as I was as a senior in college. I look at them and I see myself, and I wish I'd known then what they know now."