The Baltimore city school board has officially voted to close four middle schools this summer: Dr. Roland N. Patterson Sr. Academy and Robert Poole, Thurgood Marshall and Harlem Park middle schools. Nine elementary schools that were scheduled to add grades 6 through 8 will halt or postpone that expansion. And three other schools that had started to add the middle grades will revert to elementary grades. The district is in the process of closing several of its failing middle schools and expanding elementary schools to include grades 6 to 8. But officials have found that some elementary schools do not have the capacity for more students. Meanwhile, many of the city's middle and high schools have too few students.