Teaching students with intellectual or developmental disabilities to write: a review of the literature.

The purpose of this review was to identify effective methods for teaching writing to students with intellectual disabilities. After criteria were established, database searches and hand searches of selected peer-reviewed journals were conducted. Findings revealed a relatively small number of studies that met the criteria for inclusion. Participants, settings, research designs, independent variables, dependent variables, and results are synthesized across studies. Writing instruction effects on various written expression outcomes were aggregated by averaging percentage of non-overlapping data (PND) across studies. Findings revealed that strategy instruction was investigated more frequently than other types of approaches. Strategy instruction was consistently found to be very effective for teaching writing skills to students with intellectual disabilities. Limitations, directions for future research, and implications for practice are discussed.