In classrooms and auditoriums across the District, in offices on floor after floor of D.C. school headquarters, thousands of voices stumbled yesterday over the words of a tune to be sung on 35 miles of city streets tomorrow.

Organizers of the schools' celebration of American Education Week expect to attract 250,000 people -- including all 87,000 D.C. schoolchildren, private school students and federal and District workers -- onto the streets to hold hands and sing for five minutes beginning at 11:30 a.m.

The event, called Hands Across the City, will close almost 35 miles of streets, including all of Pennsylvania and Wisconsin avenues and numerous side streets. More than 650 police officers and hundreds of chaperons will supervise as children step off the sidewalks to sing "Embracing the City," a tune written for the occasion by Grace Bradford, music director for D.C. schools. The demonstration was designed to impress city residents and politicians with the depth and fervor of support for public education.

The human chain is expected to stretch over the width of the city from Pennsylvania Avenue SE at the Prince George's County line to Wisconsin Avenue NW at the Montgomery County border.

The halt of traffic will be drastic, but brief, organizers said. Civil defense sirens will signify the closing of streets at 11:25. Drivers will be asked to turn on their headlights and pull over for the ceremony.

If Wednesday is rainy, as is forecast, the street demonstration will be called off and the ceremonies will take place in schools, Johnson said.

The route will pass the District Building, where Mayor Marion Barry and D.C. Council members are expected to join in, and the Capitol, where several congressmen have said they will participate.