Too little playtime may seem to rank far down on the list of society’s worries, but the scientists, psychologists, educators and others who are part of the play movement say that most of the social and intellectual skills one needs to succeed in life and work are first developed through childhood play. Children learn to control their impulses through games like Simon Says, play advocates believe, and they learn to solve problems, negotiate, think creatively and work as a team when they dig together in a sandbox or build a fort with sofa cushions. (The experts define play as a game or activity initiated and directed by children. So video games don’t count, they say, except perhaps ones that involve creating something, and neither, really, do the many educational toys that do things like sing the A B C’s with the push of a button.)