It sounds awfully nice: A yearlong postponement of schoolwork. The White House announced on Sunday that Malia Obama, the president’s older daughter, would be among the thousands of students to take a gap year between high school and college. The hiatus from classrooms, textbooks and tests has become an increasingly popular choice. The idea is that university-bound students go on an adventure, do something meaningful and, if all goes to plan, arrive at campus a year later more mature, focused and attuned to their goals.