My son's school does tracking. There are two advanced classes with the same advanced curriculum. There are also 4 more classes per grade. Each class is further divided into ability groups for math and reading. Admission into the advanced classes is based on standardized test scores, grades and teacher's input. All of the gifted kids are in the advanced classes regardless whether they're high achieving. Every year, a few kids are moved up or down in the tracks.
The school does a great job of integrating minorities into the top classes. Many of the gifted and high achieving kids are minorities, of course. And many of the white kids are actually low income. You never can tell somebody's IQ or economics just by looking.
