Millions of K-12 students throughout the United States have participated in “A Classroom of Difference,” an “anti-bias” program produced by the Anti-Defamation League (ADL). The curriculum is often glowingly publicized as just what schools need to “eliminate harassment, bullying, and racial tension,” as one newspaper put it. But how much do parents and taxpayers know about the content of the program that many of their schools are rushing to adopt? The program has grown dramatically since 1985, when it began in Boston as a joint endeavor between ADL and a local television station. Today, the “A Classroom of Difference” program...