Limos and nannies drop off 3- and 4-year-olds every weekday morning at New York City's most exclusive preschools. Tuition is more than $30,000 a year. The schools boast that young kids learn French, Chinese, violin, yoga and robotics - all before kindergarten.Just a few subway stops away in the Bronx, home to one of America's poorest congressional districts, there's a very different morning drop-off routine going on.