Back then, school teachers were drawn from the educated middle class female population. That pool of people no longer goes into teaching. Now teachers are increasingly drawn from the pool of people who do not have the intelligence to do anything else, judging from comparative SAT scores for ed majors versus other majors.
That is a really key point that gets very little consideration in discussions on education. Of course these days, little that is relevant gets much consideration in most societal discussions on education.
Not entirely true from the teachers I know. What has happened is that because of the decision to reduce class sizes from 35-40 to 16 to 20 many, many teachers of marginal intelligence are now in the system, forever. The small class size does not correlate to accademic accomplishment after you control for income and professional levels of the parents.
The smaller class size is a big mistake and is probably the biggest contributor to lack of learning in our children.