One important issue of the current empirical research on special education is the investigation of the effects of inclusive education compared to segregating education for students with learning disabilities (LD). For this purpose, measurement instruments have to be appropriate for students with LD and measurement equivalent across students with…

The mission of German special schools is to enhance the education of students with Special Educational Needs in the area of Learning (SEN-L). However, recent studies indicate that students with SEN-L from special schools show difficulties in basic arithmetical operations, and the development of basic mathematical skills during secondary special…