A major section of IDEA is the Least Restrictive Environment clause (LRE). LRE is defined as the educational setting where a child with disabilities can receive a free appropriate public education (FAPE) designed to meet his or her education needs while being educated with peers without disabilities in the regular educational environment to the maximum extent appropriate. This means that we can't have self-contained classes of students with disabilities unless less restrictive settings are inappropriate. You can seee that you've got that mushy word "appropriate" in there which can, and does, cause all sorts of problems. It seems to me that "least restrictive" is often reinterpreted to mean "most convenient" and not for the student but for the teachers. It's inconvenient to have a student in your class that learns differently and/or acts differently from most other students because that means you might have to change your teaching. It's that or move the student to a different class. Which one happens most often, I wonder?
So, in my district, it's no wonder that there is a good deal of resistance to the push to include students with disability in mainstream classes by ending self-contained classes that took students away from their home schools and relegated them to spending the whole day with one teacher and a bunch of other "high needs" students - a recipe for disaster if there ever was one. That and the district office keeps reminding everyone that we have to do this because it's part of No Child Left Behind that is being enacted this year and the district got in trouble last year from the state department of ed. for having too many students in self-contained classes. Notice that no one mentions that inclusion is more ethical, leads to better educations for all and the LRE for the vast majority of students.