This is sooo very true. I had an experimental math curriculum in the 6th grade that had special sections in the book that covered (in an age adjusted way) things like axiomatic definitions of numbers, extending the field of integers to rationals, limit sequences as definitions for real quantities, fields and rings and some other topics. I was sooo revved about that class and so bummed when the next school thought math meant doing sets of 50 long division problems each night.

But the excitement didn't die off. I had a great 8th grade math teacher who noticed that I did all of the exercises in the book during the first two weeks of class and diverted me into a more advanced class (algebra) and eventually got me into correspondence courses (trig and geometry) and late in the same year into the high school calculus class. By finishing calculus that year, I was able to branch into languages and other topics.

Branching out early is a great motivator for the right kids. More interesting material can lead to explosive levels of interest in kids.