Improving assessment validity for students with disabilities in large-scale assessment programs

A test designed with built-in modifications and covering the same grade-level mathematics content provided more precise measurement of mathematics achievement for lower performing students with disabilities. Fourth-grade students with disabilities took a test based on modified state curricular standards for their mandated statewide mathematics assessment. To link the modified test with the general test, a block of items was administered to students with and without disabilities who took the general mathematics assessment. Item difficulty and student mathematics ability parameters were estimated using item response theory (IRT) methodology. Results support the conclusion that a modified test, based on the same curricular objectives but providing a more targeted measurement of expected outcomes for lower achieving students, could be developed for this special population.