I don’t see children playing outside these days. Not even in rural areas. On sunny, snowy winters, I’d expect to see children out sledding, building snow forts, or skating. In the summers, I wonder why I don’t see children out playing kick the can, or any of the myriad of other games children create when they get together. I’m not the only one who has noticed this. My adult friends say the same. I’ve seen more elderly and middle-aged people outdoors—sledding, flying down a hill, laughing, arms in the air, and then trudging back up the hill, their skin looking healthily flushed, faces open with smiles. I’ve seen middle-aged men out playing with a remote control toy airplane. You could tell from their body language they were having fun. In my youth, kids went outside after school. We were physically very active and healthy. We learned through each other the rules of fair play. We became concerned about changes in our neighborhood that affected our playing fields. We gained in coordinatio...