"And I still can't use proper grammar....so help me help yo' kids talk like me."
I saw parts of the decline over 50 years ago.
Most of the teachers I had were excellent.
A few were there to indoctrinate, not teach.
We were forced to homeschool our kids 35 years ago due to the incompetence of improperly educated educators.
There are individual excellent teachers scattered around the system, and if you are lucky, your students will encounter them.
The incompetent teachers and administrators, who tend to be leftists, whenever they can will do whatever they can to get rid of the good ones, both over politics and because the good ones make them look bad.