How do mathematics teachers grade tests? Different scoring and content priorities in micro-decisions, yet similar final grades

Grades are the currency of education, yet research on how teachers assign them remains limited. In this study, we examine the micro-decisions teachers make when grading classroom tests—small grading judgments that combine specific feedback with a partial point—focusing on both scoring types (addition, subtraction, imposing a maximum) and content priorities (e.g., conceptual understanding, procedural skills). Thirty-six secondary mathematics teachers graded 30 student tests on linear equations without predefined grading guidelines. Findings reveal four distinct clusters based on scoring types, such as teachers who consistently apply subtraction-based grading. Similarly, four clusters emerge based on content emphasis, including general praisers, who frequently provide praise with limited attention to mathematical content. While these findings reveal substantial variation in how teachers assign partial points and arrive at a total score, the analysis shows that only 4% of the variance in final scores can be attributed to teachers, whereas 84% stems from differences in student responses. In other words, teachers often take different routes toward grading, yet their final judgments tend to point in the same overall direction, challenging prevailing concerns about the reliability and objectivity of teacher judgments.