At first, A.J. Vazquez was “kinda grossed out” at the thought of seeing his guts. But it all made sense once he and 20 Coral Gables Preparatory Academy classmates began making life-size diagrams of their own digestive systems.

“This green string is A.J.’s small intestine,” said Alexander Yagoda, 10, holding up part of a rainbow-colored trail of yarn created to map the path and distance from 11-year-old A.J.’s mouth down through his intestines.

Textbooks and lectures don’t quite get Jill Gonzalez’s brainy fifth-grade math and science class going, so their advanced lessons are often hands-on, independent activities like mapping students’ bodies or tossing parachutes off the second floor. It’s the kind of class designed for a small group of Florida’s brightest students - the “gifted” - but increasingly found throughout Miami-Dade schools.

In the last decade, Miami-Dade has experienced a remarkable boom in its gifted population, much of it by design. The number of such kids has increased by more than 50 percent since 2003, to the point where more than 10 percent are now labeled gifted.

The development is unusual in a state where the rate is just 1 in 20. Consider:

• Miami-Dade’s gifted population grew during the last 10 years from 24,434 to 37,238in a district of 353,000. That’s more than double Broward and Palm Beach counties’ rate and trumped in Florida by only Alachua and Sarasota schools.

• Of the 12,804-student increase, 11,337 of them are black or Hispanic students, who throughout the country are chronically under-identified. There are now more gifted Hispanic students in Miami-Dade than in the rest of the state. White students are increasingly deemed gifted, too, with nearly one in four now qualifying.

• Certain schools are practically gifted hubs, with a quarter or more of their students placed in gifted courses. Numbers from the 2011-12 school year show the rates were generally highest at magnet schools like MAST Academy, where half the children are gifted - but they came from all over the county via lottery admission. Still, other traditional schools with geographical attendance boundaries had substantial concentrations. They include North Beach Elementary (43.1 percent), Pinecrest Elementary (35.9 percent) and Coral Gables Preparatory (30.5 percent.)

Administrators say the numbers reflect efforts to better identify and serve advanced students that began in 2006 when the Miami-Dade School Board voted to improve its programming. The district sought the advice of experts, spent millions to add services, and trained parents, teachers and principals to spot exceptionally bright students, including those unique to minorities. Services were also expanded so that every school could provide gifted education to its students rather than bus them twice a week to a gifted center, as they often did in the past. Charters still provide their own services.

After one year, the number of gifted students jumped by more than 6,000, or almost 25 percent. That was due in part to an expansion of services for older students, who otherwise would have dropped off the map because the state only identifies children receiving a gifted education.

“By expanding our services and making them available districtwide, we saw an increase in our numbers,” said Lisette Rodriguez, head of Miami-Dade’s gifted programs. “It’s the whole ‘build it and they will come.’ ”