I worked for 15 years as an ASL interpreter, before carpal tunnel syndrome benched me; I had treatment for it, and I can still have ASL conversation, so I hang out with Deaf friends all the time.
I have been studying and learning ASL my entire adult life. I achieved the core of my knowledge at Gallaudet University.
The is no written form of ASL. There are a few different systems linguists use to record it on paper in order to write articles about, or compile dictionaries, but there has never been a single, standardized system, and since most papers are online now, people have stopped trying to “write out” ASL, and just put in clips of people speaking in ASL the things they wish to discuss in their papers.
ASL is correctly termed “spoken,” and either “received,” or “understood.”
People whose only language is ASL are NOT “non-verbal.”
Deaf people who have Deaf parents, and therefore speak ASL from the cradle, statistically have the highest rates of literacy of all Deaf people in the US. (credit: PhD dissertation by Dr. Barbara Kannapell, degree awarded by Georgetown University)
The reason for the high rates of literacy among Deaf people with Deaf parents is theorized to be the high rate of language deprivation still seen among Deaf children of hearing parents, vs. pretty much zero rates among Deaf children of Deaf parents.
About 5% of Deaf people have Deaf parents.
Many Deaf children (of hearing parents) still are not introduced to ASL until age 3, when they are required to receive publicly funded education under Public Law 94-142 (1975-- the Education of all Handicapped Children); before that they may be exposed to pidgin sign, English-y signs, or just home signs and gestures. Some are not introduced to any signed language at all (even home signs are discouraged) until much later-- they must “fail” at Oralism (speaking and lipreading only) first, or fail at “hearing” school, and transferred to a Deaf school, or Deaf program within a hearing school, along with feelings of shame and worthlessness.
And many parents of ASL-speaking Deaf children do not know any “sign language,” not even half-assed pidgin sign, let alone ASL.
Most Deaf children have not been read to as toddlers and preschoolers, and have not had “reading readiness” experiences in those years. They don’t get reading readiness until they are 4 or 5 sometimes, and so when they start first grade, they are already behind, both in reading readiness, and in language acquisition. Their early elementary years are often spent just remediating this.
Some Deaf schools and Deaf programs in public schools do not hire teachers with ASL competency. Why is a story of oppression that goes back to 1880, to something called the Conference of Milan. I am not going to get started on this, or this post will never end.
But oppression is real, and Audism is real.