Let me start by saying when it comes to people with autism, there is not one-fit-all answer. Using sign language as the main method of communication is no exception; every child is different and the decision should be accordingly. However, for those who are non-verbal and who usually tend to be on the severe end of the spectrum, I don't believe that sign language is the way to go.
Using sign language requires certain skills which are often lacking in children with autism and need to be taught in isolation at first such as imitation, eye-hand coordination, and fine motor skills.
Often times, we see some basic signs taught to the child such as stop, wait, more, eat, cookie, etc. These can be extremely beneficial and helpful to the child but are limited and most of times are not expanded to a full language.
Other issues with choosing sign language as the main communication method for non-verbal autism has to do with the characteristics of autism itself as sign language is a sophisticated method and does require a certain level of executive functioning. The child has to know that signing is not visible in the dark and it does require an audience. I have often find my child pointing or signing while he is in his room and I am somewhere else in the house. Perspective taking and theory of mind play a role of how sign language can be effective.
Finally, the general population does not know sign language and is better to consider a more universal method of communication such as speech devices and typing which have their own limitations as well but are more promising and have unlimited potential.
M.Ed. Special Education/ Autism Intervention
As a mother of a non-verbal son with autism , I often hear people telling me: " You are an angel " or " I don't know how you do it " or "I don't know what would I do if I were you??!", etc. I have to admit that I feel very uncomfortable hearing that because caring for my son is the most natural thing that comes to mind and yes it is very challenging and difficult at times, but my answer to all...and to the question of "how I do it?" is I get up every morning and DECIDE that I have to do it. I put one foot in front of the other and go, and I would assume that every one can do that if they DECIDE to do it as well regardless of the circumstances because to me it is not just an obligation but it is an honor and a privilege that I am entrusted to care for someone so vulnerable like my son, and as someone once said "the measure of a civilization is how it treats its weakest members.".
When my son was insisting on closing every door we open, I used that to teach him "open" and "close". I also would sabotage the environment where I would open doors on purpose so he would ask me to close it using his Dynavox (speech device).. That worked specially well on the kitchen cabinets where he could not reach them to close them himself. In essence , instead of looking at his obsession with closing doors as a negative, you could turn it into a positive and a teaching opportunity.
The same goes for those on the spectrum with special interest. Try to incorporate their interest in the teaching materials. When I was teaching my son how to do 'word search', I took advantage of his interest in Disney characters and used them as words to search for in the puzzle. I did the same when teaching him spelling, reading, and typing.
Another application of turning a lemon into lemonade or a disability into an ability ....
Eric, my 14 year old non-verbal son with autism has no verbal speech. At some point, he was diagnosed with a very low IQ and supposedly with a mentality of a toddler. However, any one who spends 5 minutes with him begs to differ. Over the years, he has often surprised us by how smart he is and his capacity of learning things independently like how to use Google on the computer and get to Youtube on my cell phone.
I try to teach my son by providing frequent opportunities throughout the day in his natural environment. Furthermore, I tend to narrate as often as possible: what he is doing (Eric is watching Toy Story), what I'm doing (Mommy is washing the dishes), what someone else is doing (the man is mowing the lawn), or just noting a certain event (it is raining).
For example: When I notice my son is rubbing his eyes and he is sleepy, I would say "you look sleepy..It is time to go to bed". If I notice that his hands are dirty after playing basketball, I would say "your hands are dirty...go wash them". These particular commentaries will progress into "you hands are dirty..what do you need to do?", to simply making an observation "your hands are dirty" with a non-verbal cue pointing him to the sink to wash his hands. Eventually, he would be noticing on his own that his hands are dirty and proceeds to wash them independently . These examples of incidental teaching mixed with narrating, modeling, intraverbal style of communicating, using prompting/fading, all in the natural environment, could also be reinforced using structured teaching.
I designed an activity called "what do you do when...."?. If your child can read then you can just use written language. Otherwise, use pictures. I use one set of index cards for the "What to do" and another set of cards for the "when". Examples of "what to do" answers would be "wash them", "go to bed", "Turn up the volume". The corresponding "what to do" questions would be "when your hands are dirty", "when you are sleepy", and "when you can't hear the TV".
My son proceeds to match the answers to the corresponding questions. This is particularly helpful if the child is a visual learner and seeing the actions in words helps reaffirm the concepts learned incidentally.
We often concentrate on teaching skills in isolation. For example: teaching prepositions such as "in", "on top of", "over" and so forth. It is definitely good practice to teach in a structured, controlled environment with trials conducted in a systematic manner. However, it is as important to teach these skills within the context of every day use. For example: When teaching "in", you could tell the child to put the orange peels "in" in the trash, get "in" the bath tub", pour the milk "over" the cereal, stand "behind" me in the line, get "inside" the car, etc.
Write down these prepositions with a sharpie (BLACK or RED) on index card and flash them and point at them while interacting with the child when giving him such directions. It would also help point to the word to emphasize the word/preposition being taught. It is always a good idea to have a visual support and it is a good step to teach pre-reading/reading skills.