I went to a Montessori school for elementary school. It ruled. I was estimating cube roots and square roots using the binomial theorem in third grade (not that I knew I was doing that). Of course, I switched schools in fifth grade, and back to addition it was. sigh

Yep, I also saw a significant dip in the quality of my education when I began going to public school (moved and enrolled at in the 5th grade after moving). I always felt too many steps ahead of the rest of the class and was forced to slow down and wait for them. Luckily I have realized in the last year or so to take my education into my own hands and have learned to study topics on my own for my own sake.