At work I took a class on writing, about an hour of which was devoted to grammar.
The instructor passed out a sheet listing the 8 parts of speech, plus some finer points about verbs. The guy next to me, who the instructor kept calling by my name, asked, "Do you think we in America have problems with grammar because we speak American but write English?" I think he was serious.
Next the instructor asked everyone to define the parts of speech. The class did OK with noun. Also verb. With adjective there was general agreement though not a word-for-word shared definition. But after that, all bets were off. Adverb? "Any word that ends in
ly." I was the only one who could define a preposition, and by the time we got to transitive and intransitive verbs the entire class was looking at me like I was possessed by a 19th-century demon. They all took detailed notes.
After class, the instructor held me back to ask where I went to school. I told her the name of my college. Maybe she was expecting me to say Europe or something, because that obviously didn't shed any light.
A couple of hours later, I ran into someone in the bathroom who expressed amazement at my knowledge of grammar and said she'd had to study up back when she thought she was going to be a high school English teacher. She graduated from high school in '98 and had never been taught any grammar. So maybe that's why I knew and nobody else did -- they were all younger than me.