"Among professional fields of study," writes Grant Frost. "I am not sure any can quite match education when it comes to the prevalence of what I like to call 'Guruitis'," a term he uses to describe "the penchant that educational authorities have for adopting all manner of theories and practices based on the promotion of those ideas by certain 'gurus' in the field." It's a fair criticism, and the field should most properly be described by a body of science, not this or that 'theory' promoted by some leading light. The discussion turns to John Hattie's contributions as a case in point for both sides of this. Originally intended to apply rigorous method to the evaluation of instructional strategies (and more recently, related factors), it became a 'league table' used to evaluate instruction. "I find myself wondering how many young teachers faced criticism and perhaps even censure, due to an oversimplified and apparently erroneous interpretation of Hattie's research," writes Frost. "Education has never been simple, and teaching excellence can never be reduced to a checklist."