Four years ago, in cities and towns across America, millions of teen-agers entered the ninth grade. At the same time, CBS News began an in-depth examination of this group, the Class of 2000. The goal: To present a portrait of our country's problems a... (more)nd promise as seen through the eyes of these students. CBS News' 48 Hours completes this four-year project with a look at several remarkable young men and women.