American schools have been integrating students of all races since the heyday of the civil rights movement of the 1960s. Now, several schools are trying to create a mix of students by income level.

So-called socio-economic integration has resulted in higher test scores for low-income students after more affluent classmates were transferred to traditionally low-income schools. One of the reasons appears to be that the parents of wealthier students had the clout to force improvements to those schools, which poorer parents had been powerless to change.

In La Crosse, Wisconsin, for example, students from an upper-and middle-class high school were reassigned to another high school with a predominantly low-income enrolment and an inferior academic programme.

After first resisting the move, the parents of wealthier students turned their attention to upgrading the poorer school, and the low-income students started posting higher scores on standardised tests. There was no decline in achievement for the prosperous students who had been transferred there.

Parents’ insistence on better resources apparently is not the only reason socio-economic integration has an impact on low-income students.

Studies show that just associating with classmates who have higher expectations of life can have an impact on these children. One study of 60,000 Minnesota students found that the “degree to which poor children are surrounded by other poor children has as strong a (negative) effect on their achievement as their own poverty”. Another study found that children from low-income families in predominantly poor schools were three times more likely to remain poor into adulthood than low-income children who had wealthier classmates.

Other school systems also are trying this approach. Raleigh, North Carolina, is offering specialist fine arts programmes in low-income schools to attract middle-class students, for example. The gap between achievement scores for rich and poor has shrunk there.

There remains considerable resistance. Despite its earlier success, the La Crosse school system caused an uproar when it proposed expanding its socio-economic integration programme from those original two high schools to all grade levels, and to the entire city of 50,000.

Four school committee members were ousted in a contentious election. But their replacements stuck with the plan, while letting parents send their children back to their original schools if they chose.

So far, no achievement test results have yet become available to judge whether balancing rich and poor has made a difference in the expanded scheme.