A FORMER movie theater in a rundown east Washington neighborhood, the Anacostia Museum makes a poignant contrast with its show on Anna Julia Cooper, a pioneer black educator.

The museum will be 15 years old on Wednesday. It was the first neighborhood museum of its kind in the country and the first Smithsonian museum to use in a major exhibit simplified labels for those with reading difficulties.

This is perhaps the happiest of the building's many lifetimes. It still has the old marquees of the Anacostia Theater, the two lobbies, the big red exit signs. Another time it was a skating rink. It has always been a place for children.

The Cooper show, which has been up most of the year, is intense, detailed, demanding and absolutely fascinating. It takes time, for it consists not only of many fine old photos of people and places but also of documents, letters, even a slace census. It is a treasure house of primary sources.

Anna Cooper, born into slavery probably in 1858 in Raleigh, N.C., died in 1964. For more than 30 years she taught at Dunbar High School, the alma mater of several generations of distinguished black people. She was one of the first black women to graduate (in 1884) from Oberlin College. She got her PhD from the Sorbonne in 1925, a first for any Washington woman. She was 67 at the time.

The dissertation was on the French attitude toward slavery. It was written in French, of course. Her main subject at Dunbar was Latin.

Space is divided into the phases of her life, the schooling, the years as principal of the M Street School, later Dunbar, the work with the Pan African Movement (she addressed the first conference, London, 1900) and the YWCA and Settlement House, the decade as president of Frelinghuysen University.

Anna Cooper's story, not as well known as Booker T. Washington's, say, or Mary McLeod Bethune's, needs to be savored and lived in, and at the Anacostia Museum show this is what you are invited to do. The earliest photos show Lunsford Lane, a fierce patriarch who in 1829 bought his own freedom for $1,000, and Cooper's mother and brothers, whose family name was Haywood.

A bright little girl, Anna could already read and write when she went to St. Augustine's Normal and Collegiate Institute, where she helped to teach in exchange for board and tuition. She married George Cooper at 19, but he died after two years, in 1879. She never remarried. At 23 she entered Oberlin, and here again are pictures of the scholarship student and the two other black women attending that forward-looking college.

The parlor of Cooper's home at 201 T St. NW has been moved into the museum, as have a classroom and an art gallery with paintings by a student, Frank Dillion. The sense of determination and hope is powerful here, with the bust of Frederick Douglass, the fireplace tiles depicting Shakespeare's plays, the classic statues and paintings.

One comes away tremendously impressed with the role of Washington educational institutions and especially Dunbar High in giving this country a roster of black leaders.

The museum also runs creative-writing workshops, lectures and film series and programs for children. At 2405 Martin Luther King Ave. SE, it is open 10 a.m. to 6 p.m. weekdays and 1 to 6 p.m. weekends.