D.C. City Council Chairman Kwame Brown announced the next series of roundtables on the District’s troubled middle schools. Students are asked to provide insight about their experiences at a special session on Sept. 24, while government witnesses are invited to testify on Sept. 27. With enrollment in D.C. Public Schools continuing to drop off after the elementary grades, Brown is zeroing in on Ward 5, where many parents are frustrated about the lack of middle schools: He’ll hold a third, separate roundtable — the “Ward 5 Great Schools Initiative” — on Sept. 29 at Luke C. Moore High School in Northeast.