With "teach-ins," peace songs, and antinuclear movies, groups of university students in the Washington area and across the country marked Veterans Day yesterday by staging low-key nuclear arms protests.

The Union of Concerned Scientists, the organizer, said the events included meetings at 500 colleges, more than triple the number that took part in similar protests a year ago.

However, attendance at the meetings in the Washington area was generally small, a pattern that organizers said was repeated around Boston. The organizers said they had reports of larger turnouts in the South and Midwest, where antinuclear activities have previously not been widespread.

"I guess classes are a concern for people, although I think nuclear war should be of more concern," said Joshua Sarnoff, an organizer for the scientists' group, as he left a meeting attended by about 90 students at George Washington University law school.

"I would have probably liked to see the campuses closed down for a day," Sarnoff said. "But that didn't happen. If you don't have a big-name speaker or a concert, you are less likely to get people."

A lunch-hour meeting outside the George Washington University library attracted 100 people. They listened to readings of antinuclear statements by students and a campus minister, interspersed with the singing of John Lennon's "Give Peace a Chance."

At the Georgetown University Law Center, about 60 persons gathered for a late afternoon "teach-in" in a moot-court room that can seat 400. On Veterans Day last year, several students said, the room was filled for a similar event.

"It might have something to do with the nuclear freeze referendums doing well around the country," said Dean Brennen, a student from Matawan, N.J., "and there's just a letdown in activity. Or it could be the job market. Every time you hear about 10.5 percent unemployment, that makes students even more self-centered than they already are."

Adam Yarmolinsky, general counsel for the U.S. Disarmament Agency in the Carter administration, told the meeting that nuclear war would mean "extinction" and that the Reagan administration's fears of a "window of vulnerability" to Soviet nuclear attack were "nonsense."

Another speaker, David H. McKillop, a former State Department official who was active in the nuclear freeze referendum here, accused the administration of "mixing up a witches' brew for human extinction that would make Julia Child blanch."

Besides the Concerned Scientists, antinuclear groups of physicians, lawyers, and academics joined in sponsoring the "teach-ins."