In Intelligence in the Classroom, Charles Murray explains that “half of all children are below average, and teachers can do only so much for them”:
Some say that the public schools are so awful that there is huge room for improvement in academic performance just by improving education. There are two problems with that position. The first is that the numbers used to indict the public schools are missing a crucial component. For example, in the 2005 round of the National Assessment of Educational Progress (NAEP), 36% of all fourth-graders were below the NAEP’s “basic achievement” score in reading. It sounds like a terrible record. But we know from the mathematics of the normal distribution that 36% of fourth-graders also have IQs lower than 95.What IQ is necessary to give a child a reasonable chance to meet the NAEP’s basic achievement score? Remarkably, it appears that no one has tried to answer that question. We only know for sure that if the bar for basic achievement is meaningfully defined, some substantial proportion of students will be unable to meet it no matter how well they are taught. As it happens, the NAEP’s definition of basic achievement is said to be on the tough side. That substantial proportion of fourth-graders who cannot reasonably be expected to meet it could well be close to 36%.
The second problem with the argument that education can be vastly improved is the false assumption that educators already know how to educate everyone and that they just need to try harder–the assumption that prompted No Child Left Behind. We have never known how to educate everyone. The widely held image of a golden age of American education when teachers brooked no nonsense and all the children learned their three Rs is a myth. If we confine the discussion to children in the lower half of the intelligence distribution (education of the gifted is another story), the overall trend of the 20th century was one of slow, hard-won improvement. A detailed review of this evidence, never challenged with data, was also part of “The Bell Curve.”