There is a national movement to create a nation school curriculum, the same in all states. It is controversial, lotta folks think the school curriculum in their state is nobody else's business. Lot of education folks like the idea of a national standard, to which they can point, when parents press them to soften up school standards.
The common core is posted on the web and Google led me to it. I scanned the math standards for first grade thru high school. They aren't very rigorous. And the have a lot of new age time wasters. For instance they try to introduce algebraic concepts in first grade. High school geometry proves some of the easier theorems but does NOT bother to prove the Pythagoras theorem. They don't understand the purpose of high school science labs.
In short, Common Core isn't going to improve anything. On the other hand it doesn't look like it does much damage.