Advanced courses taught at many feeder schools also create an advantage. Laura Zingmond is a senior editor at the InsideSchools website, a project of the Center for New York City Affairs. Ms. Zingmond said that students from some middle schools had simply done more interesting work than their peers elsewhere.

“It’s not even that their writing skills are better, but what they’re writing about is better,” Ms. Zingmond said. When it is time to apply to high school and create a portfolio, which is required in some cases, they “will just have a lot more they can pull from.”

By contrast, Ms. Turbides, who helps middle schoolers apply to high school in eastern Brooklyn, said the opposite was often true.

“We have teachers who have no idea they need to be holding on to students’ work, and they throw it out because they have no place to put it,” Ms. Turbides said. “So for a lot of these students, when it comes time to submit a portfolio, they have nothing to submit.”

The Fair

In the imposing Brooklyn Tech building, each of the city’s five boroughs had been given a floor or two, and the high schools had set up displays at slender tables. Students rushed from one to the next asking questions and printing their names on clipboards. Many tables were sheathed in school colors and littered with swag. There were branded pens, mints and lip balm. George Washington Carver High School, a school in Queens with a veterinary program, brought along a guinea pig called Mugsy, a turtle named Frankie and a rabbit who went by Marshmallow.

“Ms. Bryant, this hallway is giving me a heart attack!” a Pelham Gardens student named Tabitha Gonzalez called out on one of the floors devoted to Manhattan schools. “There are so many schools I just don’t even know.”

On the floor for Bronx schools, the halls were quieter, with fewer students exploring what they had to offer. Bronx schools find themselves on the wrong side of many important measures. They had the lowest graduation rate in the city last year, at just 65 percent. Of the students who should have graduated, more than one in 10 had dropped out.