Depending on who you talk to, Memphis is rapidly becoming one of the best cities to teach in America—or one of the worst.

For Amanda Montgomery, a 24-year-old teacher, for instance, the takeover of her elementary school by Aspire Public Schools—the California-based charter network—has brought smaller class sizes and more-consistent mentoring. “I have a lot more coaching … and supports,” she said. But Sarah Kennedy-Harper, a veteran special-education teacher at Memphis’s Northside High School, aggressively opposed a similar takeover at Northside, knowing she could lose some job security. “I need to pay my bills,” Kennedy-Harper said. “I can’t afford to be at a school where they could hand us pink slips at any time and say, ‘We don’t need your services.’”

The city’s schools are on the vanguard of controversial changes reshaping urban education nationally, including decentralized control, more charter schools, increased use of data to determine which schools stay open, and a greater reliance on new teachers who come through alternative preparation programs such as Teach for America or the Memphis Teacher Residency.

At the heart of these changes is the state-run Achievement School District, created in 2010 with the intent of turning around Tennessee’s lowest-performing schools. Some of the schools are run by state-appointed officials; others are turned over to charter operators. Of the 16 schools pulled into the Achievement District so far, 15 of them are in Memphis. A locally elected school board continues to run most of the city’s schools, and the city also has charter schools that are independent of the Achievement District.

The Memphis landscape epitomizes what a growing number of educators and public officials describe as portfolio management: when an array of operators—a traditional district, the state, charter operators, community groups—run some of a city’s schools instead of a single entity maintaining control. Schools’ very existence hinges on test-score gains. Those that underperform are, like weak stocks, transferred, repackaged, or dropped outright.

Supporters argue that the strategy saves children from attending chronically underperforming schools. Critics maintain it treats educators and students like widgets that can be reshuffled without regard to the human toll. Other cities pursuing comparable models include New Orleans, Chicago, and Philadelphia.

Tennessee’s Achievement District is modeled in part on Louisiana’s state-run Recovery School District, which absorbed most of New Orleans’s schools after Hurricane Katrina. In Memphis, where state officials plan to increase the size of the Achievement District to about 22 schools by next fall—turning several of the schools over to charter operators—the response has been decidedly mixed.

When a charter group took control at Cornerstone Prep last fall, for instance, some parents and community leaders complained that school leaders and teachers lacked cultural sensitivity and instituted overly harsh rules. Other parents have come to appreciate Cornerstone’s hardworking teachers and intense focus on academics. “There are two teachers to a class,” said Sharanda Thomas, whose son is a fifth-grader at the school. “It’s more hands-on. I think it’s better all the way around.”

The Achievement District is still in its early stages, but the reception so far underscores a key challenge facing similar efforts across the country: Will communities embrace schools run by largely unknown and private organizations? How important is community acceptance? And, for that matter, who even constitutes the community?