Arlington Superintendent Arthur W. Gosling plans to recommend Thursday that the School Board require high school students to take seven classes a day, a first for Northern Virginia public high schools.

Gosling said yesterday that an increase in the number of courses required by the state and more rigorous college admissions standards have forced students to give up such elective courses as art and music. The additional class also would give some students a chance to participate in an advanced science program under consideration by the board.

If adopted, the seven-class day would begin next school year. The increased schedule would cost "in excess of $500,000," Gosling said, with most of the cost coming in salaries for additional teachers.

"I think it's the only way we can make a substantial increase in opportunities for kids," said Gosling. "It's not a panacea . . . but it would be helpful."

Arlington high school students are required to take six classes a day. Montgomery County is the only school system in the Washington area that requires a seventh class in high school.

Arlington schools have 14,400 students.

In recent years, the expanding list of state-imposed requirements has significantly reduced the choices students have about their schedules and left them little time for electives, school officials said.

In the early 1980s, the Virginia State Board of Education added one math and one science course to the high school graduation requirements. This year, it added a requirement for either a fine arts or practical arts course but did not increase the time a student spends in school.

Three years ago, after a long study and much debate, the Arlington School Board rejected adding a seventh class, citing a million-dollar price tag and lack of community support.

As an alternative, the school system increased its summer school offerings, the number of courses offered through a Saturday enrichment program and the number of courses offered before and after normal school hours.

Those ideas "haven't worked out as well as we would have liked," said School Board member Dorothy Stambaugh. "I think the timing is absolutely perfect for a review" of the matter.

The proposed science program includes courses in biology, chemistry and physics that are more advanced than the advanced placement classes now offered. It calls for opening high school science laboratories on Saturdays, offering double-period classes so that laboratory work can be more efficiently conducted and may include short-term courses in such fields as genetic engineering, microbiology, biotechnology, spectrophotometrics analysis, optics and lasers.

The program is projected to cost $278,702 for the first two years and includes a "total examination, selection and revision" of the system's science programs from kindergarten through 12th grade. About $50,000 would be used to buy new equipment.