“Schools are supposed to introduce children to a variety of ideas and viewpoints, but the Miami-Dade School Board decided a few years ago to put one viewpoint off limits. It banned the children’s book ‘A Visit to Cuba’ from its school libraries because it said the book offers too positive a portrait of life under the Castro regime. That was bad enough, but then last week, a federal appeals court upheld the ban. The Supreme Court should reverse this disturbing ruling.”