My brother and I are close in age and one of my favourite memories from childhood is playing with him outdoors unsupervised almost all day (how are we still alive? how did we not burn down our grandparents' house?) or lip syncing to 70's pop music while jumping all over my parents living room furniture.
A Serious Conversaton About Play. Enlightening interview. h/t to playground parents & this NPR article: http://n.pr/1d848Wd