It is becoming a much more common sight to see children with special needs in the mainstream classroom. Children suffering from Autism or Asperger's Syndrome are among these who are being introduced into the mainstream environment.
This is not harmful to the Autistic children as long as they are understood and taught in the correct manner. And it is up to us, as teachers, to learn all we can about children with Autism so that we can meet their needs fully in order to enhance the learning experience.
Before you meet a child with Autism or Asperger's Syndrome, it is important to know that these children generally do not like to be touched. This is not because they do not like you or that they're scared of you, it is because of sensory integration problems which these children suffer from; touch is often misinterpreted as pain.

Often, eye-contact is extremely poor and if the child has not been taught to provide eye-contact, it will be one of your first projects. Even if the child has learnt eye-contact, Autistic children and children with Asperger's Syndrome will need prompting in this area; they are not ignoring you, they just don't know the subtle rules of conversation and also battle to pick up non-verbal cues.
Try to stick to a routine and, if you know it will change at some point, be sure to prepare the child for the disruption of their daily timetable. Often, change is not handled well and should be dealt with very delicately, preparing them days, or weeks in advance.
If Autistic children have a tendency to line up their belongings in a certain way, this is normal. Slowly, by building a relationship with them, you will be allowed to move something or rearrange things in order to show them that you can play with them too. Autistic children love the order in lining up toys and belongings; it is calming and gives them a sense of control.
Asperger's Syndrome presents a different challenge. These children tend to be more verbal and seem to know a large amount of information; they always correct you and seem highly driven to learn. While this is somewhat true, teachers often miss this. Asperger's Syndrome sufferers will need to be taught, lovingly, in the area of listening and avoiding the desire to correct others.
This is a small amount of insight into the world of Autism and will help you with the first steps of teaching.