I don't really understand the comments saying that the CC is being used as a curriculum. This isn't possible, because it's just a list of standards:

Quote
CCSS.MATH.CONTENT.1.G.A.1
Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size); build and draw shapes to possess defining attributes.

The Common Core is simply a statement of what children should know. A challenge with implementing it is that it's mathematically correct, and textbooks have had a problem in that area for a long time. Another major problem is that many teachers don't understand mathematics well enough to teach it properly, and they're hindered by the poor textbooks. This hasn't changed much with the supposed alignment of textbooks with the Common Core.

Indigo, the developers of the Common Core never had any involvement with the textbook companies, nor did they "support" them. Plus, the textbook companies never had any influence over the Common Core.