Autism and learning to play a musical instrument??

Try the keyboard, It's often a good idea to indentify a musical note with a colour and felt tip the key of the instrument. It could be something you both have fun doing together, it's also a great way for him to negotiate seperate parts of his brains into working at the same time. He'd essentially be doing two very complicated things at once, but they'd be designed to entertain and relax him unlike conventional education paradigms.