So, what is Common Core? As Bob Lonsberry explains:

Common Core is the nationwide public-school curriculum that is the centerpiece of Barack Obama's' Race To The Top' program. It tells America's teachers what to teach and how to teach it. It makes Washington the master of American education and, consequently, the master of the American mind. That's why conservatives don't like it. They believe it's indoctrination, not education ... and they're probably right. Liberals don't like it because it essentially castrates the teaching profession. The individual abilities, insights and creativity of teachers count for nothing. It's a repudiation of about everything America stands for. Local control is lost, federal supremacy is established, the people's voice is ignored. The parents and teachers of your community mean nothing, the president and his planners mean everything, your children's developing minds become receptacles for a one-size-fits-all liberalism, imported from far away.

Rachel Alexander wrote in her Mar 18, 2013 piece at Townhal titled Common Core: What's Hidden Behind the Language:

[...] Superficially, it sounds good. It creates universal standards that supposedly educate all children for college. But along with the universal standards come a myriad of problems, which the administrators of Common Core are disingenuously denying. The American Principles Project released an analysis last year of Common Core, exposing the duplicitous language. Common Core describes itself as "internationally benchmarked," "robust," "aligned with college and work expectations," "rigorous," and "evidence-based." None of this is true.

tch, a former assistant U.S. secretary of education who was appointed to office by both Clinton and George H.W. Bush, recently changed her mind about Common Core. Ravitch now refutes claims by Obama and Common Core that the standards were created by the states and voluntarily adopted by them. She writes in The Washington Post, "They were developed by an organization called Achieve and the National Governors Association, both of which were generously funded by the Gates Foundation. There was minimal public engagement in the development of the Common Core. Their creation was neither grassroots nor did it emanate from the states." Instead, Common Core is being driven by policymakers in D.C.

[...] The curriculum replaces the classics with government propaganda. According to the American Principles Project, "They de-emphasize the study of classic literature in favor of reading so-called 'informational texts,' such as government documents, court opinions, and technical manuals." Over half the reading materials in grades 6-12 are to consist of informational texts rather than classical literature. Historical texts like the Gettysburg Address are to be presented to students without context or explanation.

The math standards are equally dismal. Mathematics Professor R. James Milgram of Stanford University, the only mathematician on the Validation Committee, refused to sign off on the math standards, because they would put many students two years behind those of many high-achieving countries. For example, Algebra 1 would be taught in 9th grade, not 8th grade for many students, making calculus inaccessible to them in high school. The quality of the standards is low and not internationally benchmarked. Common Core denies this on its website as a "myth," but Professor Milgram's opposition contradicts this. ... Read the whole thing here...

Related: Teachers Against Common Core.