The kids' shot at a music career is gunned down by Peter's prepubescent vocal strains and Greg's song, "A Time to Change." The episode also marked the debut of their other pop ditty, "We Can Make the Whole World Brighter." Peter: Christopher Knight. Carol: Florence Henderson. Dimsdale: John Wheeler. Greg: Barry Williams. Alice: Ann B. Davis. Bobby: Mike Lookinland. Marcia: Maureen McCormick.