"When you let students work at their own pace -- we see it over and over again -- you see students who took a little bit extra time on one concept or the other, but once they get through that concept, they just race ahead. And so the same kids that you thought were slow six weeks ago, you now would think are gifted. And we're seeing it over and over again. It makes you really wonder how much all of the labels maybe a lot of us have benefited from were really just due to a coincidence of time."