The school’s parent coordinator, Harvey Blumm, said that when he visited middle schools whose enrollments were overwhelmingly black and Latino, it was not uncommon to find students who had never heard about the specialized high school exam; or to meet students who had signed up for the exam, but had never thought of taking a practice test or prep course — something common among white and Asian students; or to have guidance counselors tell him that Stuyvesant “isn’t for our kids.”

RUDI, who lives in the Wakefield section of the Bronx, attended sixth and seventh grades in Jamaica, and eighth grade in Mount Vernon, a Westchester County suburb. Her father, Donovan Miller, a director of accounting at Bronx Community College, recalled asking a colleague for advice about enrolling Rudi, the youngest of his three children, in “the best New York City high school.” The colleague advised Mr. Miller that he had to sign her up for the specialized high school exam and, if he wanted to improve her odds, to have her take some kind of test preparation program.

Many Stuyvesant students start preparing for the exam months, even years, in advance. There are after-school, weekend and summer classes run by large companies like Kaplan and Princeton Review, as well as by neighborhood outfits like Aim Academy, in the predominantly Chinese enclave of Flushing, Queens, and the Khan’s Tutorial branch in nearby Jackson Heights, home to thousands of families from India, Pakistan and Bangladesh.

Rudi took Kaplan’s 12-week program, which met on Saturdays at Fordham University, at a cost of $750, the summer after seventh grade. (Students take the exam in October of their eighth-grade year.) Her tutor, a Stuyvesant graduate, persuaded her to make the school her first choice.

Her mother, Annmarie Miller, a nursing assistant at a hospital in the Bronx, recalled a cousin’s reaction when she mentioned Rudi’s pick: “You have to be Chinese or Indian to get in there.” A co-worker, also black, “said the exam is built to exclude blacks because it’s heavy on math, and black people can’t do math,” Mrs. Miller said.

Rudi said she has never felt uncomfortable at Stuyvesant, but she has felt puzzled. She has been the only black person in most of her classes, and often goes hours without seeing another. The school’s attendance sheets have names and pictures of the students, and she said teachers were quick to learn who she is; there are few others like her, she said.

For Rudi, being black at Stuyvesant has been a journey of self-discovery. In Jamaica, as in parts of the Bronx, it is not skin color that distinguishes people, she said, but the car they drive, the neighborhood they live in or the job they have.