MIDDLETON, Idaho (AP) — Robin Gilbert didn’t set out to confront gender stereotypes when she split up the boys and girls at her elementary school in rural southwestern Idaho.

But that’s exactly what happened, with her Middleton Heights Elementary now among dozens of public schools nationwide being targeted by the American Civil Liberties Union in a bitter struggle over whether single-sex learning should be continued. Under pressure, single-sex programs have been dropped at schools from Missouri to Louisiana.

“It doesn’t frustrate me,” Gilbert said of the criticism, “but it makes the work harder.”