There is a focus in the article in playing outside which is good and fine.<p>But another important aspect missing today is age mixing. This is crucial because it is an informal mentoring process, in effect. 4 year olds learn best from being around 6 year olds who learn best from 8 year olds, etc. up the chain. There is also reflection from being a mentor to the younger ones. All of this is absent increasingly today.<p>It is not just lack of recess or whatever, but a lack of neighborhood, of community. The young ones learn how to share, how to regulate emotions, etc., in part by witnessing the older ones being that way.