Hillsborough County was part of a recent nationwide effort to improve schools from the top down, through a project known as the "principal pipeline."
The idea is that a strong, well-trained leader can boost student performance, particularly in struggling schools. Research has shown the approach works. But Susan Gates, senior economist at the RAND Corporation, says a key question remained.
"What was missing was a sense of whether these things could be done by districts at scale to really move the needle for all students."
An eight-year RAND study found that the principal pipeline boosted reading and math scores, and made economic sense, costing less than one half of one percent of the district budget.
Robert Bhoolai did six years of preparation to become a principal at Robinson High School in Tampa.
"It used to be managerial role but today it is so much more than that," he said. "The principal really functions as the instructional leader of the campus. "
After three years, schools with new pipeline principals saw scores in reading improve by six percentage points, and almost three points in math.
Gates said the approach was affordable, costing just $42 per student each year, and it works because principals are supporting the teachers.
RAND calls the improvements "statistically significant and meaningful," and on par with the scores-boost seen in schools that engage in Teach for America, a program that recruits motivated instructors to work for two years at schools in need.