As Chancellor of the Washington D.C. schools, Michelle Rhee entered a system in which 90% of its students were failing standardized tests. After she left, 90% of the students were passing the tests.
This is how she did it. The interview, well worth watching, is fairly long but much more comprehensive than her critics would like. The interview in its entirety — a must watch for anyone interested in turning around urban failing schools — may be found here.