Concerned over the decline in scored on college entrance exams and the flight of many city students to private schools, D.C. School Superintendent Vincent E. Reed has proposed opening a new high school that would offer a more rigorous academic curriculum than any other school in the city.

School officials who have worked with Reed on the proposal for the "model high school" stressed that it would not be just for the gifted student. Rather, it is aimed mostly at the "average student," one who is functioning at the proper grade level but may not be challenged by the current high school curriculum.

Cecily Middleton, an executive assistant to Reed who worked on the proposal, called the need for such a model school "a statement that our high schools, nationally, are not doing the job we hoped they would do."

The proposal calls for limiting the number of electives the student can take because too many electives, the proposal assert, "can do real academic harm to students." Instead, students at the model school would be required to take at least two years of mathematics and science and four years of social science and English.

There would be the additional requirement that all students take three years of a modern language and three years of a classical foreign language. There are currently no language requirements for high school students.

Students also would be required to work part of the school week in the community or school to relieve "the obvious boredom, potential for destructiveness and pent-up energy of teen-agers."

This is the second time in three years that school officials have proposed a "model school." The last time, the idea was criticized both by parents in the wealthier school districts of upper Northwest, who felt it would drain their community high schools of its best students and parents from the poorer neighborhoods of far Southeast, who called the plan "elitist."

Over the years the school system has had difficulty steering its good students toward advanced programs because of a 1967 court decision that ordered the dismantling of a "tracking" system that rigidly separated students in class according to ability.

Last year, D.C. public school students had the lowest college board test scores of any Washingon area school system and placed in the bottom 20 percent among all students taking the test nationwide.

The low performance level of D.C. students has driven many middle-class families in the city to place their youngsters in private or parochial schools. About 17,500 city students attend private and parochial schools. The enrollment in public shcools in 113,050.

"In past years, there have been many programs for underachievers and slow learners. We've neglected to a certain extent the average and better than average student," said Patrticia McCrimon, assistant principal at Cardozo High School and a supporter of the proposal.

"This is a way of saying [to average students] 'We haven't forgotten you.'"

The model school would be located in an existing school facility, with easy access to public transportation.

The 700 to 900 students it would serve would have to be performing at or above grade level in reading and math, submit three recommendations, go before a panel of school officials and their peers, and write an essay on why they want to be part of the program.