I find it telling that the article breaks down scores by race, not by income.  Note that it claims that the difficulties are for <i>low income families who cannot afford tutors / other resources</i>, not <i>black children</i>.  What's the crossover?  What's the pass ratio for <i>poor</i> white children?<p>Granted, a book can easily be harder to read / understand for less-classically-trained children.  I'm not saying it's not possible, just that the article is definitely seeing what it was looking for.