In this study, we present an approach to questionnaire design within educational research based on Guttman's mapping sentences and Many-Facet Rasch Measurement Theory. We designed a 54-item questionnaire using Guttman's mapping sentences to examine the grading practices of teachers. Each item in the questionnaire represented a unique student scenario that was graded by teachers. Three focus groups of elementary (N = 5), middle (N = 4), and high school (N = 2) teachers examined the scenarios for clarity, comprehensiveness, and ease of understanding. Based on the suggestions of the focus groups, the revised questionnaires were completed by 516 public school teachers located in a major metropolitan county in the Southeast. The grades assigned by the teachers to the scenarios were analyzed using the FACETS computer program. The results of the analyses suggest that teachers primarily assign grades on the basis of student achievement as expected, although for some teachers other facets (ability, behavior, and effort) may play a role in final grade assignment.