From the joy of smearing glue on paper to the screaming delight of a bubble-blowing relay, kids love to play. In fact, it's every kid's built-in tool for experiencing the world at large. A parent-friendly encyclopedia, UNPLUGGED PLAY ("A wonderful guide," says Daniel Goleman) offers hundreds and hundreds of battery-free, screen-free, chirp-and-beep-free games and fun variations that stretch the imagination, spark creativity, building strong...