Over the last ten years or so, schools have put more emphasis on curricular on-task time, often shortening recess as a result. The idea is that kids will learn more if they spend more time in the classroom and less time on the playground. As I observe my kiddos everyday, I know that the education experts who promote this line of thinking have it exactly wrong. Obviously they do not understand the workings of a school or classroom and make rules based on their ignorance. They THINK something will gain a desired result and don't bother to consult the real experts, the teachers, before codifying these decisions.
When kiddos are deprived of enough time to run and play, their classroom studies suffer. Twenty minutes of recess per day is not nearly enough time to nurture well-rounded kids. With too little time for recreation, kids' focus suffers and they try to have recreational experiences in the classroom. Right now, we hear all kinds of positive stories in the news about education in Finland. It is the hot topic right now. I read about how schools in Finland operate and know one thing to be true - the amount of time that schools there devote to recess and recreation is one reason that the kids perform so well. They seem to understand that when kids run and play for long periods of time several times per day, their focus in the classroom sharpens and they can learn more in less time. Our focus here in the USA has been on quantity of time instead of quality of time.
I see the kids' pent-up energy in my own classroom. While we try to include lots of activities in which kids can move and use their social skills, class time is no substitute for recess. Kids need play time and lots of it. A school day in which kids have thirty minutes of recess three times per day would be ideal. We would see kids learning when they should be learning and playing when they should be playing. Now, we often see kids playing when they should be learning because there is so little time to play. Play is an essential part of being a kid. Kids need unstructured play time. It fosters their imaginations, helps build social skills and gives them a chance to exercise their bodies.
In our "more is better" culture, we miss an essential point. We mistake quantity for quality. If we want kids learning more then they need to play more. We have to build pockets of time into the day during which kids can burn off some of their energy and be kids. When kids have those times, several times per day, then they will focus more in class and learn more. It is not rocket science. It is what the best school systems in the world are doing.