What do we know about uniforms?

American schoolchildren often wear uniforms if they attend religious or other private schools. Most public schools do not require uniforms. But over the last ten years or so, more of them have moved in that direction, including high schools.
    Students may have to wear a specially purchased uniform. Or they may just have to dress alike—for example, white shirts and dark colored pants or skirts.
    Even schools that do not require uniforms generally have a dress code or other rules about what they consider acceptable. Policies commonly ban clothing that shows offensive images or words, or simply too much skin. Items like hats may be restricted because, for example, different colors may be connected with violent gangs.
    Some parents like the idea of uniforms. Some say it means they do not have to spend as much on clothing for their kids. Others, though, argue that uniforms represent an unnecessary cost. There are also debates about whether uniforms or other dress policies violate civil rights.
    Students and parents have taken legal action against school dress requirements. Just last week, a judge blocked a middle school in Napa, California, from enforcing a dress code unless families have a way out of it.
    The American Civil Liberties Union of Northern California brought the case for the families of several students who were punished. Most attention centered on a girl who wore socks with the Tigger character from Winnie the Pooh.
    The school said its clothing policy, including no pictures of any kind, was needed to control a growing problem with gangs. The families argued that the policy violated free speech rights as guaranteed by the United States and California constitutions.
    The United States Supreme Court says student expression is protected as long as it does not harm the work and discipline of a school.
    Americans value individual freedom. But some educators believe dressing alike helps improve student learning. They believe that uniforms help create a sense of unity and reduce the risk of fights. They also say uniforms make it easier for security reasons to tell if someone belongs at the school or not.
    But just how effective are school uniform policies? Studies have found mixed results. That will be our subject next week.