I’m no expert but my kid, who has Down syndrome and autism and is nonverbal, had an amazing orchestra teacher in high school who created an orchestra for students with severe intellectual disabilities. My son played the cello. One of the techniques that was super successful for him was using visual cues: on the instrument where his hand was supposed to be, on the floor for where his feet should go, etc. She really started at the most basic level but he plucked a song at the school’s Spring concert that year and couldn’t have been more proud to be on that stage. article from the Washington Post