Deborah Kasak, executive director of the National Forum to Accelerate Middle Grades Reform, said research is showing that all students benefit from mixed-ability classes. “We see improvements in student behavior, academic performance and teaching, and all that positively affects school culture,” she said.

Image Aidan Bracken, left, and Evenson Andre in class. Credit... Christopher Capozziello for The New York Times

Daria Hall, a director with Education Trust, an advocacy group, said that tracking has worsened the situation by funneling poor and minority students into “low-level and watered-down courses.” “If all we expect of students is for them to watch movies and fill out worksheets, then that’s what they will give us,” she said.

In Stamford, black and Hispanic student performance on state tests has lagged significantly behind that of Asians and whites. In 2008, 98 percent of Asian students and 92 percent of white students in grades three to eight passed math, and 93 percent and 88 percent reading, respectively. Among black students, 63 percent passed math, and 56 percent reading; among Hispanic students, 74 percent passed math and 60 percent reading.

The district plans to keep a top honors level, but put the majority of students in mixed-ability classes, expanding the new system from sixth grade to seventh and eighth over three years. While the old system tracked students for all subjects based on math and English scores, the new one will allow students to be designated for honors in one subject but not necessarily another, making more students overall eligible for the upper track.

The staff of Cloonan Middle School decided to experiment with mixed-ability classes for the last eight weeks of this school year.

David Rudolph, Cloonan’s principal, said that parents have long complained that the tracking numbers assigned to students dictate not only their classes but also their friends and cafeteria cliques. Every summer, at least a dozen parents lobby Mr. Rudolph to move their children to the top track. “The zero group is all about status,” he said.

Jamiya Richardson, who is 11 and in the twos’ group, said that students all know their own numbers as well as those of their classmates. “I don’t like being classified because it makes you feel like you’re not smart,” she said.