There are students from more than 70 countries attending D.C. public schools, and in the coming school year 18,000 students are expected to study foreign languages.

In an effort to deal with the increasing diversity of its student body and to meet the demand created by the requirement that secondary school students study a foreign language, the public school system has sent teachers of French and Spanish back to school this summer. The teachers will take part in a program aimed at reshaping the focus on foreign language in the classroom.

The District's department of foreign language, in collaboration with Georgetown University's School of Language and Linguistics, was awarded $155,000 by the National Endowment for the Humanities for a four-week institute and two post-institute seminars to be held between the summer of 1986 and the spring of 1987.

A major objective of the institute is to help teachers respond to their students' curiosity about lives, values and customs of young people in various Francophone and Hispanic cultures.

Said Marian Hines, project director and supervising director of the foreign language departments of the District's schools: "The world is a classroom; the world is larger than your community."

The institute focuses on literature from Spain, France, West Africa, Latin America and the Caribbean.

Twelve French teachers and 11 Spanish teachers are participating in the summer program, which ends tomorrow, and all agreed to live on campus for the four-week period. During that time, they participated in lectures, discussion periods, lab sessions, movies and reading periods.

Carolyn Reed Wallace, assistant director of the division of education programs for the National Endowment, said this is the first grant of its kind to be awarded to a public school system. Such grants are usually given to colleges and universities, but Reed said the District did its homework in preparing its application.

"Marian Hines wrote a first-rate application, one of few in its nature. They presented a very clear intellectual rationale for wanting the grant," said Wallace, who said the District had competed with Ivy League universities for the grant.

Wallace said Hines demonstrated that D.C.'s public school system has a number of outstanding teachers. She added that the National Endowment has funded only three grants examining the child in Francophone and Hispanic literature. The others went to the Hampton Institute in Hampton, Va., and New York University.

Hines said she is especially proud that the District school system received this grant for an education project since the schools have been under fire for problems with drugs and violence. She said the application for the grant resulted in part from a survey in which teachers said they needed more cultural background to strengthen their skills in the classroom.

She said the school system later took the idea to Georgetown because the university has the only school of languages in the area and because of the District's relationship with Georgetown on other projects.

Hines got lucky because two Georgetown lecturers have done dissertations on the same subject: "The treatment of the child in Francophone and Hispanic literature."

The institute has nine faculty members, including three district teachers and professors from Georgetown University, Howard University and the University of the District of Columbia.

Hines said the school system employs 120 teachers who give instruction in six languages -- French, Spanish, Latin, German, Italian and Russian. French and Spanish are the most popular languages, she said.

The 23 program participants are mainly from D.C. public schools but there are a few from Maryland schools. The participants were selected based on results of a proficiency test and a 200-word essay, along with meeting certain guidelines developed by the foreign language department of the District's school system.