One person who acknowledges my observation that America's pre-1970s textbooks contained harder problems is David Griswold, my source for the Exeter math curriculum. On Dan Meyer's blog, Griswold write:
In the 1960s, textbooks had harder problems in them because the vast majority of Americans never came close to completing high school, so those books were never seen… To pretend the American textbooks and education of that era are superior to now is simply to ignore the fact that very few students ever used them, and those that did were a select, privileged, and talented few.Apparently a reasonable response to the broader number of students attending high school is to dumb down the curriculum for everyone (including those who are less privileged but equally talented). Of course, this is what has happened--and is happening even more with full inclusion.
Why not instead make those mathematically superior pre-1970s books available to everyone and let students proceed through them at their own respective paces?
Convincing people to do this, however, involves challenging some other, deeply held beliefs: that only today's "21st century curriculum" prepares students for "21st century jobs"; that all students learn best in heterogeneous ability groups; that the more advanced students deepen their understanding when they explain math to the less advanced students; that the less advanced students appreciate being taught by the more advanced students; that children are as good at teaching one another as certified teachers are; and that we shouldn't worry about students who advance to the next level of math possibly being "math zombies."