Blackboard-WarsThe man who used to lead Roanoke City Public Schools is now part of a series on the Opera Winfrey Network.  Marvin Thompson was the superintendent in Roanoke from 2005 to 2007.  He’s now in charge of John McDonogh High School in New Orleans. The school’s been plagued by low test scores and violence.  Last year, a nonprofit group was brought in to convert the campus to a charter school.  Camera’s for the OWN Network are following Thompson, the teachers and students to see if they can turn things around.  Blackboard Wars airs Saturday nights at 9:00.  Thompson’s two year stay in Roanoke came with mixed reviews.  Some test scores went up, but a number of teachers left the school district under his leadership.