Over the past five years I've looked at countless student performance numbers, and almost always, my attention goes to the large percentages of students who are performing below grade level in reading, math, history, etc. I see these numbers as evidence of the failure of the current education system.The high performers are suffering in this system, too.

But a recent policy brief (titled "How Can So Many Students Be Invisible?) has brought something else to my attention—something equally, if not more, damning of the education system. It's the fact that large percentages of American students are performing ABOVE grade level.

After looking at data from five different, nationally-respected assessments of student performance, the researchers found that "20-40% of elementary and middle school students perform at least one grade level above their current grade in reading, with 11-30% scoring at least one grade level above in math."