Many children growing up in Western countries cannot become healthy, self-sustaining adults without immediate attention and, in many cases, without specialised support. Depending on the severity and perseverance of the difficulty, a high percentage of children require this attention and support. Over the past twenty years, the percentage of students with disabilities served in schools and classes with their non-disabled peers has gradually increased. As the percentage of students served in settings with non-disabled students rises, the number of special education, regular education teachers...