I've been helping my daughter with her homework a lot lately. She's in sixth grade and has not yet outpaced my rudimentary knowledge of mathematics. But there's still a problem--while I can work out solutions to her problems, I can't explain where they come from. Or more precisely, the way I figure things out is incorrect, according to whatever it is she was taught.
So while I can tell her whether or not she arrived at a correct conclusion, I am no help whatsoever in leading her to it. My methods are just outdated and useless, not to mention totally unacceptable on tests.
Tom Lehrer wrote about the New Math in the 60s. Almost half a century later parents are still struggling with it.
But he can explain it much better than I would. Enjoy.