Only 10% of public-school districts in the U.S. sort children as young as 4 years old into separate gifted-and-talented classrooms and schools. Unfortunately, New York City, the nation’s largest district, is among them.

At the 11th hour of his administration, Mayor Bill de Blasio called for an overhaul of this program, which uses standardized tests to track children even before they enter kindergarten. But his successor will be responsible for making sure a much-needed course correction is carried out.

The obvious reason for making the change, which leaves the city’s selective high schools untouched, is that the system worsens racial and economic segregation. Three-quarters of the students enrolled in gifted-and-talented programs are White or Asian. Meanwhile, 70% of all New York City students are Black or Hispanic, and a majority attend schools where less than 10% of their classmates are White.