The school bell peals. Doors fling open and a thousand teenagers spill into the halls.

"You know the rules, people, " a man bellows through a bullhorn. "No headphones. No hats. Get your ID badges out and get moving!"

Students have six minutes to crisscross the sprawling two-block campus. When the bell rings a second time, classroom doors shut and the halls are strangely quiet.

Loitering is not an option.

There's too much at stake.

Miami Central -- a high school historically beset by chronic truancy, declining enrollment, dispirited staff and general disrepair -- is fighting to avoid a grim distinction. It could become the first school in the state to face a federally mandated overhaul because of repeated failures on the Florida Comprehensive Assessment Test.

Over the past five years, the school has received five consecutive F grades. One more, and Superintendent Alberto Carvalho will be forced to make radical changes under a new federal mandate.

That could mean stripping the curriculum down to its bare bones -- cutting art, music and electives -- and replacing dozens of teachers and administrators, including the principal.

Carvalho could even shut down the 50-year-old school.

Enter Doug Rodriguez, the state's No. 1 principal, now at the helm of the school with the state's worst academic record.

Rodriguez, a 20-year veteran of the school system, left a coveted job at a top high school on a mission to shake things up at Central.

In a two-month flurry, he cleaned up the halls, shipped dozens of troubled students to alternative schools, designated a dean of discipline, appointed as many as four teachers to the same classroom and boosted morale.

And when The Miami Herald sought to chronicle Central's efforts to meet the challenge, Rodriguez and Carvalho agreed, giving a reporter and photographers unfettered access.

"Things are changing around here, " said Shelby LaBeach, 18, a senior who is Miss Miami Central, the official student ambassador. "We have our own Obama."

ROCKET BOULEVARD

Miami Central Senior stands on Rocket Boulevard, a stretch of Northwest 95th Street in West Little River named for the school mascot.

The school's 1,600 students come from a hodgepodge of neighborhoods, including Opa-locka, Miami Shores, North Miami and El Portal.

More than half are from low-income families. About 14 percent are enrolled in special-education programs.

The students take pride in their marching band and turn out en masse for football games -- especially when the Rockets play the rival Northwestern Bulls.

But administrators have had difficulty controlling gang activity and violence in the halls. During the 2005-06 school year, more than 1,100 students received in-school suspensions. The following year, only a third of Central students said they felt safe at school, according to a district survey.

"Kids were bringing the streets into school, " said André Young, 17, a senior and the drum major in Central's marching band.

Central also struggled academically. Last year, 10 percent of sophomores passed the reading portion of the FCAT, compared with about 30 percent districtwide and 38 percent statewide.

Hundreds of students opted to leave, taking advantage of a state program that allows transfers out of low-performing schools to other public schools.

A decade ago, former Gov. Jeb Bush unveiled his A+ Plan for Education as a way to bring accountability to struggling schools like Central.