So, as a service provider, there have been many incidences where I worked with a student who could not speak to me…Literally. I would say “throw” or “jump” and they would look blankly at me or start demonstrating behaviors such as disengaging from the task, dropping themselves on the floor, of even running away from the situation!!

When having to work with a child who can not communicate using words, I remember, “find other (non-verbal) ways to reach them.” 

Strategies that often work
For self regulation, Building rapport and  successful engagement are: 

smiles, friendly tone, singinging (they are nonverbal but they can hear and comprehend!!

Visual engagement: lots of colorful and shine, light up toys

Deep pressure toys and activities

Routine in engagement: this will bring a sense of security with the child and ability to gain their trust .

Music👍

Demonstrations :shown (with singing) then gesturing “your turn”

Tactile and physical prompting may become more necessary in these cases.

In the end, remember, these children are nonverbal, however they are still children. So, just as demonstrations of joy, friendliness, patience, acceptance, and love go a long way with verbal children. The same will go (if not more so) for children without words.