There are several problems with the systems of mathematics education in many states, ... Math today is much more visual and conceptual and each lesson builds on the previous lessons. ... California ...

Mathematical modeling --- Reflective of the power of mathematics to provide frameworks and conceptual tools for building, using, and refining abstracted representations of many real world phenomena ...

Conceptual understanding and fluency are both important parts of math education, and it could be that the shift to conceptual math instruction was not a problem, or was just one of several factors.