DID YOU KNOW that Thomas Jefferson was a member of Washington's first school board? Or that Florida Avenue, less than two miles from the White House, was once the city's nothern boundary? Or that 14th and U Streets Northwest is the city's oldest crossroads? If you did't, you're probably not alone. Most Washingtonians don't either. The written history of the city has been largely that of the federal enclave; with few exceptions, the place behind the monuments has remained unknown, unstudied and misunderstood - even by its own citizens. For example, Alexander (Boss) Shepherd as a political folk figure probably ranks right beside New York's Jimmy Walker and Boston's James Michael Curley, but we'd bet not many Washingtonians know who he was or the prominent location of his statue.

Recently, however, District school officials have mounted on effort to dispel the ignorance of Washington's local history by establishing a year-long required course in junior high school. This recognition of a crucial missing element in the schools' curriculum is noteworthy. Even more important, in our view, is the careful way school officials and the consultants helping them are developing this new course.

Two years ago the D.C. School Board approved the addition to the schools' curriculum of a mandatory course in local history. Assisted by Associates for Renewal in Education, a local think tank with close ties to the school system, a special team of junior high school teachers wrote a pilot teaching manual for the course. But they also found that developing such a course on a broad scale would be tougher than they had expected. One reason is that there is a dearth of readily accessible information on local history. Another is that most of the information that exists is to be found in scholarly works, museum catalogues of Washington-related exhibits and out-of-print books. Finally, there is the sad fact that even the material that is available doesn't include much in the way of biographies of local people, information on various ethnic groups in the city or the growth of various neighborhoods. In effect, a course in Washington's history will almost have to be built from scratch.

That is what school officials and ARE propose to do. They've enlisted professional historians from area colleges, the staffs of the National Archives, the National Portrait Gallery and the National Collection of Fine Arts; and private citizens who have a wealth of information about Washington's local history. ARE is now seeking a grant from the National Endowment for the Humanities to underwrite part of this projected three-year effort.

There is always the danger, of course, that such a local history program could turn out to be dry and parochial, a sort of Local Pride 101, if you will, an exercise in empty boosterism. But the range of people involved in this effort and their conviction that one can't study the local history of Washington without also studying national events greatly reduces that possibility. We think there are several reasons, educational and otherwise, to support this effort. In recent years, innovative school programs in Washington and elsewhere have proved that the study of an area's past can be a powerful incentive for young people to study history generally. And a greater knowledge of Washington's local history - or, to put it another way, the development of a "local memory" - could build a greater feeling of civic responsibility among the electorate. That would not be an insignificant consideration either.