I taught high school 1959-61 at Los Gatos in California and 1967-1987 in L.A., and I was an adjunct professor of writing for those who did not pass the state tests at Polk Community College in Florida aka for the immature the 13th grade.
I have taught AP European History, US and World History, Ctreative Writing and 11th grade English. When I began teaching, a boy could get in trouble for chewing gum, needing a shave or haircut, having a shirt tail out, and punishment was a paddling. If two boys wanted to fight, the coaches accomodated them by having them put on the gloves and go three rounds.
I saw a steady decline in the preparation of students over those years. When I began in 1967 at Fairfax in L.A., 85% went on to college. 20 years later when I left, of those who entered in the 10th grade, 75% graduated.
Academically, the best schools in the L.A. school district became similar to the economy of a 3rd world nations. The brightest and hardworking overachievers declined in number relative to the growth of semi-literate uninterested and unmotivated pupils. After my hiatus from teaching, I found the abundance of cellular phones, texting, and iphones to be more important than what any professor had to say.
The decline in my opinion has been caused by too many factors.
1. The breakdown in discipline caused mostly by fear of ACLU lawsuits.
2. Parents who expect their children to go on to college are more concerned about their kids getting good grades rather than learning (who gets the Ds and Fs at the big university? one may ask)
3. Too much middle management of curricula.
4. Anti-intellectualism in the public schools and teaching departments at the Universities -- emphasis on making the student feel good rather than teaching them subject matter and critical thinking. At Fairfax, our department, of which I was chair voted not to accept any ST from UCLA until they changed their methods -- to quote the Ed Dept Chairman, "I find that those who teach subject matter are more heartless in dealing with students' needs."
5. Women's Lib -- bright women can now become professionals, CEOs, whereas in the past they went into teaching in greater numbers. Not enough good teachers coming into the classrooms. A Sociology major, PE major, Econ Major, cannot adequately teach solid U.S. History.
6. U.S. History was a year class when I took it in high school 1947-8, a year course when my parents took it, and a year course when I taught it. It needs to be taught each semester.
7. If any child is afraid to go to the bathroom, find another school -- which leads to --
8. A combination of parents who can afford it or will sacrifice sending their kids to private or parochial school plus an influx of non-English speaking students who may or may not attend regularly.
9. Power of teachers' unions who defend the worst teachers "to the death" -- by the way, hve you ever heard of a union going on strike when a teacher is assaulted and demanding safe schools?
10. Parents uninvolved, plus too much TV and video games.
I might add there are some great public schools, but you have to look for them. In San Francisco, I attended an elementary school that was attached to San Francisco State Teachers College back in 1938-40 before we moved. We had a master teacher and up to eight student teachers per class. They taught Spanish and gave no letter grades. We could go as fast or slowly in any subject as our IQs allowed.
Later I attended one of the great academic public high schools in the USA, Lowell in San Francisco also the oldest west of the Missippi. Today, nearly all their classes are AP.
Sorry about the extensive rant -- and I could write pages on the subject.