A recycling revolution is going on through the halls of North Andover Middle School. Students, teachers and other staffers have cut the volume of trash from the cafeteria by more than half, according to Craig Richard, one of the teachers who helped get the program going. The three lunch periods at the school used to produce around 30 bags of trash per day, Richard said. "Now it's around a dozen," he said. Tod Workman, school custodian, pointing to a cart that was about half full of trash bags, said it used to overflow with refuse from the cafeteria. The recycling renaissance was spearheaded not by adults, but by two eighth-graders, Douglas Starrett and Harry Ustik, who wrote a letter to the school's online newspaper NAMS Knightly News, in which they took the school to task for throwing away too much trash.