Within the autism community there are some who choose to refer to individuals with autism as being "high-functioning" or "low-functioning". I personally have never been fond of either of these labels, but in particular object to the use of the term "low functioning". Even if one chooses only to use the term "high-functioning autism", by association, the term low-functioning is implied as being present and relevant for some individuals. My opposition to the term "low-functioning" is that the term is almost always been used to describe students who are non-verbal and have no conventional strategies for demonstrating what in fact they understand.
A dear friend and one of the most important professional mentors with whom I have worked, Anne Donnellan, always told us "the absence of evidence is not evidence of absence". Too often professionals make assumptions about individuals based on this persons inability to tell us what they understand. In this same vein, Amy Sequenzia’s Non–speaking, “low-functioning article explores this in more detail and provides good food for thought and reminders for us to be mindful about the assumptions we make about all individuals with autism, particularly those who are non-verbal.
"The criteria of the least dangerous assumption" -- another GREAT quote from Anne Donnellan, tells us that when we must make assumptions about individuals, we must make assumptions that empower and support individuals as opposed to those that limit and impede their possibilities.
What assumptions have you made and are you making about individuals with autism. Are you seeing them as "low functioning" based on what they can't conventionally tell or show you? Or are you presuming competence. I hope the latter.