Let's not forget the drastically increased time and effort spent towards self-esteem exercises, PC influenced "history" courses, healthy injections of white guilt, courses on "tolerance", sexual education and various other forms of "navel gazing" since the early 1960s.
Combined with the general dumbing down of critical courses like mathematics, language and science, as well as removing competition between students through grade inflation, affirmative action, and social promotion, it's no wonder we're spending all this money for far worse results.
Don't have kids unless you can educate them yourselves or send them to private school. Also, if your kid does go to a PS, don't think it's any different than any other because they are all de-facto owned and operated by the NEA/AFT cabal.
It's a mistake to assume that before the 1960's, public schools were bastions of academic excellence. If you research their history, they have had problems from the very beginning.
More than any one factor, way the material is presented that is the problem. Whole-word reading instead of phonics (formerly called the alphabetic method) is just one big example. Everything is presented in a dull, repetitive, assembly-line manner, in which sitting still, being quiet, paying attention to the teacher, and waiting for permission is the core cirriculum, while developing thinking and reasoning skills aren't all that important. The educational problems we face now are simply the fruits of a schooling system the country adopted in the late 1800's. The only way to change things for the better is to stop using public schools.