These are some of my favorite teaching tips for high-functioning autistic children.  I have used many of these with my son and they have worked great.

1.  If a child throws a book on the floor, avoid asking vague questions such as "why did you do that?"  Always be as concrete as possible when communicating with these children.  Instead of the vague question, tell the child, "I don't like it when you throw your book when it is time to do your homework. Next time, just tell me that you are angry."

2.  An increase in difficult behaviors is usually an indication of added stress. Stress is often caused by a feeling of loss of control. It is helpful to give the child an opportunity to remove himself from the stressful situation by allowing him to physically leave the room until he can regain control of his emotions.

3.  Don't take misbehavior personally. Autistic children are not trying to make your life difficult. Most of their bad or unusual behavior results from them trying to survive experiences that are confusing, disorienting, or frightening. Their autism makes them egocentric and they have great difficulty in reading the reactions of others.  They don't understand social cues or sarcasm and they ascribe a literal meaning to anything that is said.

4.  Prepare the child ahead of time for changes in routine and scheduling. If the child knows in advance that he will have a substitute teacher or the school will hold an assembly when he normally has math, he can deal with the change much better. More than anything, these children crave routine and sameness. They can become very upset when things change unexpectedly.  We used to tell our son that we were going to leave the park after he went down the slide two more times.  This helped prepare him to leave, instead of just telling him abruptly that it was time to go.

5.  Don't verbally spar with your child when he has homework to do. Once you are certain that he understands the assignment, tell him that you are leaving for 10 minutes to go into another room and that when you return, you expect him to be on the third problem.  You are removing his ability to delay doing the work by simply leaving him alone with his book and paper and no one to talk to or argue with.  I've also found it helpful to clear the work area of any distractions at all that could divert his attention to the task at hand.

I'll add more tips as time goes on.  Please try some of these and let me know if you have any success.