...I'm not sure why I'm not following Chad Orzel's blog! (I have actually been following Kate's LJ for a while, so am vaguely familiar with the doings of SteelyKid and Pip, although had forgotten their precise ages.) That is really cool. I've also been looking at the Common Core standards for fractions (nominally for C., although we never did get to going over them in detail) and very much like the idea of being taught why math is the way it is. If C. had been taught Common Core correctly, I think it would actually have helped her a lot. (Who knows whose fault it was, but she was certainly not taught correctly or at least well.)