Four years into their school turnaround initiative known as the Innovation Zone, education leaders in Memphis are seeking to move schools from triage to sustainable student growth, while their counterparts in Indianapolis are exploring several school improvement models that provide more freedom to drive student achievement.

Foundational to all the work is increased autonomy for principals — a strategy that brought leaders from Indianapolis to Memphis on Monday to learn best practices and to examine the role of student achievement in providing accountability for that administrative flexibility.

When Shelby County Schools launched its iZone in 2012 with seven of the state’s worst-performing schools, it gave its principals the authority to hire and fire staff and rewrite curriculum, in addition to providing other flexibilities such as lengthening the school day and providing bonuses to attract the best teachers.

The iZone now operates 18 Memphis schools, and continues to expand based on steady student test score gains. Last year, most iZone schools saw their math scores rise and, bucking a statewide trend, many raised the proportion of students meeting the state’s standards in reading.

The school board for Indianapolis Public Schools approved a plan last October to give some principals more freedom over instruction, training and budgets — and hold them accountable for student achievement. The implementation and accountability structure is still being ironed out, but the school system plans to pilot six schools next year under the model.

The Indianapolis district also has launched an Innovation Network, in which schools are managed by nonprofits or charter networks. The network has five schools so far, and four more are scheduled to join the initiative next year.

Monday’s visit from Indianapolis officials marked the iZone’s second high-profile tour in the last month by an out-of-state district. In January, school leaders from D.C. Public Schools in Washington toured the iZone.

In addition to representatives of Indianapolis Public Schools, the latest visitors included city officials and representatives of The Mind Trust, a nonprofit education organization.

The Mind Trust has been a key driver in school reforms taking place in Indianapolis. Supported by a network of foundations and major corporations, the group called for a massive overhaul of Indianapolis Public Schools in a 2011 report. Most of the report’s ideas, including more autonomy for schools, an expansion of preschool and a slimmer central office, have come to fruition.

In Memphis, the Indianapolis group visited Douglass K-8, an elementary and middle school that was part of the first cohort of iZone schools. The school improved its math proficiency from about 17 percent to almost half on last year’s state tests. Gains in reading and language arts have been slower but steady, increasing from a 15 proficiency in 2011 to 27 percent last year.

Operating an iZone school is expensive, costing Shelby County Schools about $14,500 per pupil, including special education students. Leaders in Memphis are looking for ways to wean those schools off of expensive improvement supports while continuing academic growth.

“You can’t be in the ICU forever,” said Sharon Griffin, the iZone’s regional superintendent, comparing the iZone to an intensive care unit of a hospital. “We’re into lifestyle changes.”

Griffin told the Indianapolis contingent that a proposal is in the works to create a department within Shelby County Schools that would allow schools exiting the iZone to access some of the additional supports.

She also stressed the importance of cultivating a talent pipeline and giving principals autonomy to pick their team.