Teachers' decisions are based on certain criteria which teachers believe can justify what happens in their classes. Identifying and measuring those criteria requires multiple approaches in order to triangulate the data as thoroughly as possible. In one case study of a fourth grade teacher, a repertory grid technique was used as the format for a series of in-depth interviews to supplement classroom observations and other interview data. Each subsequent interview generated an increasingly evolved description of teaching that revealed interesting and new associations when the same information was presented to the teacher in a different format. A variety of explanations for the new perspectives are presented, along with recommendations for future research.