We lived in South Carolina for a year.
At that time, high school seniors were required to pass a test to graduate. They started giving the test in 10th grade to give them a couple of extra chances.
When my dyslexic 10th grade son took it and passed it the first time, (with no help nor accommodations for his dyslexia) yet some of the seniors who were supposed to graduate couldn’t pass the test on their third try, I knew something was terribly wrong.
I didn’t feel a bit better when his Algebra teacher told us he was the best-prepared student in the class- and Algebra was a daily struggle for him, with his dad helping.
The same son was told by a classmate “you talk so sophisticated!” He was born and raised in Georgia until moving to Texas. I never was sure if she meant that he had a halfway decent vocabulary, or that he actually enunciated his words clearly enough that you could understand what he was saying.
Of course I have to say that some people are pretty much not educable. I had a high school grad here in Texas ask me, on one winter’s day, why was I so cold? “After all, you’re from Georgia, and Georgia is close to New York, and New York’s cold all the time!!” If you’re dumb as a box of rocks before you go to school, there may not be much they can do with you.
Well that's just isolation and lack of travel. When I worked a project in NYC, I regularly came across college graduates - sometimes engineers - that had no concept of anything outside of the city. Texas in particular is so large that it gets viewed like a whole country by its inhabitants. From one edge to its furthest isn't all that much shorter than the distance from Georgia to NY.