In the Classroom: "Poor Kids" and Reading

The latest to give his list of summer reading books for kids is Nicholas Kristof, op-ed columnist for the New York Times.  In "The Best Kid Books Ever" Kristof writes:

In educating myself this spring about education, I was aghast to learn that American children drop in I.Q. each summer vacation — because they aren't in school or exercising their brains.

This is less true of middle-class students whose parents drag them off to summer classes or make them read books. But poor kids fall two months be