Ronnie Screwvala sat crossed-legged on the floor of a three-room schoolhouse in early November in Nate, a village about 100 miles from Mumbai, formerly Bombay, the city of his birt,where he built a billion-dollar media conglomerate. Watching a group of children playing with colorful educational games, Screwvala, a boyish-looking 54-year-old, appeared as wide-eyed and engaged as the students.