The Alexandria School Board approved a plan last night giving more weight to junior high school foreign language and social studies programs than to art and music.

Responding to efforts to boost low enrollment in social studies courses by making them a requirement, school board members approved a "split-elective" system. Under the plan, most of the city's 840 eighth-grade students will be required to take either a social studies course in American politics or citizenship or a foreign language course, with an option to take both. Students also will take a course in music or art or a special elective such as journalism.

The system, offered last month by board member Timothy Elliott, is considered a compromise by school officials, who have been barraged with heated arguments on both sides of the issue from arts, language and social studies teachers.

Enrollment in eighth grade social studies courses has declined by 60 percent since the board classified it as an elective in 1979.

Roy Smith, the system's fine arts curriculum specialist, said the new plan proves that school officials don't understand "what the arts in general are and what they can do."

School Superintendent Robert Peebles maintained that the new system will "not devastate the art or music program."

In other action, the board approved a pilot course in motel/hotel operation. It will be taught by distributive education teachers at T.C. Williams High School beginning next year.