Development and psychometric validity evidence of a curriculum-based and adaptive mathematics assessment tool

Effective instructional decision-making in mathematics requires timely and accurate assessment of student learning. This study provides validity and reliability evidence for an adaptive mathematics assessment tool designed to support teachers in identifying areas where students need instructional support. A total of 4,875 Chilean students from fifth to eighth grade participated in the calibration of an item bank. Validity evidence was collected from four sources: test content, response processes, internal structure, and relationships with other variables. Reliability was assessed using a test-retest approach. The results provide validity evidence and reliability estimates that support the use of the tool for formative purposes. The assessment is well-suited to the Chilean educational context, offering a practical solution for evaluating mathematical learning and informing pedagogical interventions. Furthermore, the tool’s framework serves as a model for developing adaptive mathematics assessments that can be adapted for use in other Spanish-speaking regions or countries seeking data-driven instructional practices.