WASHINGTON, Sept. 20 - The public schools in Norfolk, Va., which over the last seven years have steadily narrowed a wide gap between white and black students in reading and mathematics scores, have won this year's Broad Prize, a $500,000 award to the urban school district making the greatest strides in student achievement. The prize was announced on Tuesday at a ceremony at the Library of Congress by Eli Broad, the founder of the Broad Foundation, which is dedicated to improving urban school districts across the country. "In our circles this is really the Nobel Prize of education," Stephen C....