Peter Dunn and Margaret Marshman present the second of their data files articles in which they discuss the statistical investigation cycle which describes the whole process of conducting a statistical research study. [For "The Data Files: A Series of Articles to Support Mathematics Teachers to Teach Statistics," see EJ1259108.]

Over the course of their kindergarten through twelfth grade education, children in American public schools will spend the equivalent of one school year under the guidance of a substitute teacher. Yet in most districts, substitutes are given the keys to the classroom without a day's training. While requirements vary by state, some may hold advanced…