The funny thing is is that students have been saying this in my math classes for 30 years. So why weren't they taught that way? I have to assume that I am not the only math teacher educator advocating for a conceptual approach to teaching math? Every college math ed. text I receive for review stresses the importance of helping children understand what they are learning; every conference presentation I attend stresses the same thing as do the math coaches I work with. The bridges amth prgram used on many schools throught the country also focusses on this worthwhile goal. It's been this way for thirty years at least.
I find it hard to believe that elementary school teachers are just not putting into practice all the things they learn through pre-service and in-service activities. Perhaps it is the students who do not remember learning the material in such a way. Perhaps the experiences they have in high school overshadow the things they learned in elementary school? Perhaps they just don't remember learning it this way when they were in elementary school. Too many students have these aha moments to say it is just isolated students who did not have good math teachers.
The classic example form Monday night wa the use of base-ten-blocks to teach decimals, something I have been doing seemingly all my life, yet none of the students had experienced such a thing. It is indeed, a mystery of monumental proportions.