This paper describes a feasibility study to determine whether measurement at the lower end of the student distribution, including measurement for students with disabilities and English language learners, could be improved by introducing “accessible” blocks that are aligned within the NAEP content frameworks, but designed to provide more information about the abilities and skills of students at the lower end of the distribution.

Panels of mathematics content experts and item writers were convened to identify major themes and dimensions that affected item difficulty in mathematics and to develop general strategies for reducing difficulty without compromising content and construct validity. The resulting Item Modification Guidelines and Item Modification Procedures documents were used to modify a sample of Grade 4 and Grade 8 item blocks to create accessible blocks, which were then field tested.

Field test results were promising: showing that the accessible items could be scaled with other NAEP mathematics items and did provide more information for students at the lower end of the scale.