Cyril Lang met his five English classes at Bethesda-Chevy Chase High School yesterday, and among other things, he told them he was a stickler for attendance.

For the past year, Lang himself has been most notably absent from Montgomery County classrooms. The portly teacher with the salt-and-pepper beard was removed from classroom duties in August 1980 after insisting on his right to teach unauthorized classics by Machiavelli and Aristotle to his 10th-grade English classes at Woodward High School in Rockville.

But yesterday, the man who pitted his principles against his principal and gained nationwide fame as a symbol of academic freedom was back where he had been for the last 18 fall semesters: in front of an audience of freshly scrubbed young faces, many of whom knew him from recent appearances in People magazine and on the Phil Donahue show.

"Everyone was saying, 'Oh, you got Mr. Lang,' " said Marilee Orr, a 15-year-old junior who got Lang for seventh period. "He really has made celebrity status."

"I had Mr. Lang in fourth period, and I learned three new vocabulary words," said Jamie Barse, a senior whose father, school board member Joseph Barse, voted against suspending Lang last May. "Tautology" was one of the new additions to his vocabulary, but by the end of the first day, young Barse had forgotten the two others.

Lang, usually outspoken, played down his return because his case is still on appeal before the Maryland State Board of Education. But he was relieved to be teaching again. For the last year, he had been assigned to the school system's research department where, among other things, he weighed lunchtime leftovers as part of a school system study of plate waste in cafeterias.

"After the Siberian exile, it's great to be teaching," Lang said. "I'm anxious to get back, but it takes a while to knock the rust off the edges."

The Montgomery County school board voted 4-3 last May to suspend the 55-year-old teacher for a month after finding him guilty of insubordination and misconduct.

Lang, who is viewed in some quarters of the county school system as a model of mulishness, had clashed frequently with the principal of Woodward over his use of Aristotle's "Poetics" and Machiavelli's "The Prince" in 10th-grade English classes. Makers of the school system's curriculum had decreed that the texts were too difficult for sophomores.

Lang disagreed and continued to teach and give tests on the books. He appealed his suspension to the Maryland State Board of Education, where it is pending.

For the time being, Lang said he will steer clear of the classics that got him into trouble, and he plans to keep his fight with the school system out of the classroom. He said he was content with the textbooks the school system supplies for juniors and seniors at B-CC. "They're not easy," he said. "They raise provocative questions about life and society."

His new colleagues have given him a cordial reception and his new principal, Carl Smith, said he sees Lang as just another teacher in B-CC's 90-member faculty.

"He's just one of the staff," Smith said. "As far as I know he's competent, and I expect to have a good relationship."

"The start of each school year is like opening night, especially if you've been away for a year," said Lang, who was a drama major and theater director before he turned to high school teaching. "It's a little strange to come back, but I hope for a successful year."