The Jewish Day School, a $2.7 million facility at 1901 E. Jefferson St., Rockville, was dedicated Sunday, fulfilling a long-held goal of many Jews in the metropolitan area.

This fall, 402 youngsters in kindergarten through 11th grade will attend classes in the modern, one-story school, located on 10 acres near the Jewish Community of Greater Washington.

The Rockville site is the school's first government home. During its 11 years, it has been housed in rented quarters in several Maryland locations close to the District line. The construction of the school was accompanied by controversy over whether it should be built in the city.

The dedication ceremonies were attended by 800 people who heard speeches from Israeli ambassador Simcha Dintz and Stuart Eizenstat, domestic affairs adviser to President Carter. Dinitz's 15-year-old son attends the school, as does Eizenstat's six-year-old son.

Both men spoke of the "importance of perpetuating Jesish values and culture," as the reason they had enrolled their children in the school, which includes both Judaic and secular studies.

"The number of Jews has dwindled significantly in the U.S.," Eizenstat observed, "making it very difficult to perserve cultural identity."

Years ago, ethnic neighborhoods were common, making it easier to retain one's religious heritage, he said. But today because of assimilation this has become more difficult. "So it means you must go the extra step to maintain your basic ideals," Eizenstat said.

During the nearly two-hour dedication ceremony Robert H. Smith, president of the Greater Washington Jewish Community Foundation, presented keys and a 99-year renewable lease to Julius M. Levine, school president, and Rabbis Solomon Burack and Albert H. Berliner, headmaster and associate administrator, respectively.

The foundation under the chairmanship of Charles E. Smith raised the funds to build the school. The building was named in memory of Smith's first wife, the late Leah M. Smith.

Appearing pleased with the new school surroundings were a group of 10th and 11th graders, some of whom had been members of the first Jewish day school class.

Rebecca Weintraub, 16, of Silver Spring, said she enjoys a much closer relationship with her teacher than her counterparts in public schools because the average class size is 18 at the Jewish day school.

For two hours a day, Jewish day school students are given religious instruction. Hebrew is spoken exclusively during the sessions. Many of the youngsters have spent summers or portions of the school year studying in Israel.

The remainder of the day's classes are geared to secular study. The school maintains Montgomery County curriculum standards.

While some of the students said that public school offered a better social life, most agreed that the cohesiveness of the student body make up for a smaller circle of friends.

Athletics is an integral part of the curriculum too. Michael Pratt, 14, is a member of the school's basketball team. His team competes against area parochial schools.

Student Ilana Bernstein, who attended public juniro high school in Bowie before coming to the Jewish day school, said she had grown more aware of herself and her identity as an American Jew since enrolling in the religious school.

According to school guidance couselor Shulanth Elster, it is this identity and the support received from parents that limits discipline problems at the school and keeps the percentage of students going on to college at nearly 100 per cent.

Shelley Heller of Silver Springs, whose two youngsters attend the school, said many parents make a sizable sacrifice to send their youngsters to the school at the $1,400 a year tution.

But she gave the importance of "turning back to a more concentrated Jewish education and being aware of one's religious heritage" as the reason her two youngsters attend the school.

The school offers up-to-date educational facilities. A skylighted multimedia center houses the library, study carrels, video presentation center and a reading skills room. All 27 classrooms are positioned around the center. The kindergarten opens on to a semi-enclosed play area. The upper school wing, which contains grades 7-10, features science laboraties and a darkroom. A gym and multipurpose room provides space for assemblies, sports events and lunch.