The study from the Center for American Progress, found, among other things, that "37% of fourth-graders say their math work is 'often' or 'always' too easy." These same fourth graders scored more poorly than a dozen other countries, in math.
A solid majority of American eighth graders—57%—"say their history work is 'often' or 'always' too easy." All the more shocking when you consider that only 17% of 8th graders are "proficient" at history.
Furthermore, "39% of 12th-graders say they rarely write about what they read in class." That matches almost identically the percentage of U.S. adults with "basic or below basic levels of proficiency" in literacy.
The god damn kids doth protest too much, methinks. (That's from a book. Google it.)