When it comes to brain development, time in the classroom may be less important than time on the playground. "The experience of play changes the connections of the neurons at the front end of your brain," says , a researcher at the University of Lethbridge in Alberta, Canada. "And without play experience, those neurons aren't changed," he says. It is those changes in the prefrontal cortex during childhood that help wire up the brain's executive control center, which has a critical role in regulating emotions, making plans, and solving problems, Pellis says. So play, he adds, is what prepares a young brain for life, love and even schoolwork. But to produce this sort of brain development, children need to engage in plenty of so-called free play, Pellis says. No coaches, no umpires, no rulebooks.