When you look back at New Math (ca. 1965) and Reform Math (ca. 1990), one of the most striking and persistent features was that parents could not understand the homework their children brought home.
Mystified parents were trying to advise mystified children. The parents, presumably the wise members of the society, were helpless to say anything useful when confronted by the weird complexities of “reform” math, which has now been rolled forward into Common Core.
Here is a commonplace horror story that can stand in for millions of others: “When Mike and Camille Chudzinski tried to help their son with his homework earlier this fall, they were bewildered. The fourth-grader brought home no spelling lists, few textbooks, and a whole new approach to solving math problems. When he tackled multi-digit addition, for instance, Patrick did not just line up the two numbers and then add the columns, as his parents had been taught to do. Instead, he sketched out a graph with a series of arrows and marks that appeared at first to his parents as indecipherable as hieroglyphics.”