NPR recently aired this story about how researchers are discovering that play helps the brains of children develop better skills for learning. One of the takeaways is that countries with schools that have more recess time tend to have higher academic performance.
Considering that many public schools are cutting recess in order to have more instruction time, maybe they are actually doing more harm than good. This also might help explain why many Antioch School graduates do so well in high school and college even though the Antioch School hasn't followed the push for more and more testing. Listen to the story here.