During my coursework to become a special educator, I spent time in regular schools, where the special ed. classes were usually located at the end of a hallway, separated from the rest of the school both physically and figuratively. There were really only two groups of spec. ed. students at that time: "Educable" or "Trainable" mentally retarded. The first group received what is best described as a watered-down version of the regular curriculum and little or no opportunities to mingle with their more typically developing peers. The latter group (TMR) were believed to be "trainable" at best and thus were presented with a school day that focused on teaching them functional life skills and managing their various behavioral problems. Even as I type this, it pains me to put all of this into words - but I am simply trying to describe things as they existed in those days. I have heard elaborate theories about how we all do what we can with what we know and try to do the best we can with what is known at the time. I guess this is a good example of that theory.
I also was required to spend time in our local institution for children who fell below the cut-off point for TMR, or perhaps had serious medical or behavioral issues that made the level of care needed prohibitive for a typical family in their own home. The truth is that most parents of kids with more severe disabilities were strongly urged to place their young children in such an institution as early as possible. It was seen as the best thing for everyone involved --- the child would be cared for and the rest of the family could have a "normal" life at home. Many of the parents I knew in those early years told me their family doctors had recommended (very sincerely) that they not risk getting "too attached" to a child with disabilities; the assumption being that they wouldn't be with them for long.
In the institution where I spent most of my volunteer hours, I remember stark visions of a large room filled with metal cribs, and of course in each of those cribs a child lying helplessly and usually quite passively. In yet another huge room, there were all the kids with Down syndrome: linoleum floor, plastic furniture, and virtually noting in the way of stimulation (no TV, toys, books, or anything else!) The only ones who received any type of instruction were a few kids who had hydrocephalus and were transported very carefully in a sort of wagon to the classroom for maybe an hour of "school" each day. All children were fed, bathed, changed as needed, and from time to time given a small dose of staff attention - if an occasional compassionate staff member found time in their busy schedule.
There was at the time yet a third group of children with disabilities in all of our communities - those who lived at home, lovingly cared for by their parents but seldom seen even by their immediate neighbors. There were no day programs for them unless individual parents worked together to arrange and fund such a program - usually beyond the ability of families already stressed to the maximum by the impact of the child on the family - both emotionally and financially.
The term "learning disability" was not yet in use, and I am quite sure I had never heard the term "autism." This was the mid- to late- 1960's in Wisconsin, and I would assume across most of the U.S.