Before you can decide the best way to teach a nonverbal student, it's important to evaluate him properly to see what he is capable of doing. Having him meet with a developmental therapist or psychologist will help determine if your student is able to communicate adequately through typing. Some levels of autism leave students unable to communicate through typing or sign language.
Nonverbal students with autism often have reduced motor skills in their arms and hands, so communicating through handwriting may be difficult for them. Allowing them to type may help increase communication speed between you and your students. It will also increase the amount of dialogue, allowing for more detailed communication.
If you have a nonverbal student in a class with verbal students, it's important to place him as close to the front of the class as possible. Minimizing distractions will help him focus and communicate directly with you and the other students. If he is typing on a computer, you will be close enough to respond quickly to any question or answer he may have.
Positive reinforcement when teaching your nonverbal students to communicate through typing will help give them the courage and self-esteem to push through difficult tasks. Each time a student successfully communicates or learns a new facet of typing, reward him with praise or a prize such as a sticker. Making typing lessons into games, such as speed-typing or typing-accuracy games, will also help improve your students' communication skills.