I was an early supporter of the Common Core, and signed a public statement of support for the standards on behalf of One World Secondary School some time in 2010, if I recall correctly. The basic concept is right: we live in an increasingly mobile society, and my international experience (I taught overseas for seven years, and have visited 23 countries) has made me keenly aware of the differences in educational attainment between Americans and other people. This has motivated my long struggle to start an international secondary school for my son and for as many students who want to be educated like him as I can find.
A consequence of this long (and still ongoing) attempt to start an international school for everyone has been extensive study of the world's educational systems, including their mathematical standards. Really top level standards can be easily accessed through the website of APEC, the awkwardly named Asia Pacific Economic Cooperation, and its human resource development group wiki.
I am sorry to say that I have withdrawn support for the Common Core, largely because of the lack of international competitiveness of its mathematical standards. Common Core mathematics will leave American students roughly three years behind their Chinese, and two years behind the other leading Asian mathematics students, who are increasingly arriving on American shores to take the SAT, a test whose mathematics are laughably easy (they really laugh at them; I have tutored many such students over the years) compared with what they have studied during their secondary school careers. And the problem is getting worse, as an article I've just read today from the Pioneer Institute makes clear; and it will likely lead to the dumbing down of the SAT, a test already terribly inferior to the university entrance examinations most of the rest of the developed world's students study for, with malignant consequences for the future of the U.S. voting public and its engineers, in particular.
A parent I work with who is concerned about her son's future prompted me to write something on this topic. I wish I had something more encouraging to say to her. My only message to her, and to other parents like her who are worried about their children's future, is to find a way, if at all possible, to withdraw your children from their state schools, enter private education to the extent you can afford to (but check out their mathematics curriculum, which may be no better), and press for vouchers to help you afford this better alternative (like One World Secondary College!), at least until the Common Core mathematics standards are withdrawn for revision; and don't listen to any reactionary siren songs favouring a return to some imaginary good old days: those have never existed, in American secondary education, and our children need to be prepared for a competitive future, not for some fantasyland of the past, nor for an unreachable No Child Left Behind national state that at present is cut off from the realities of the other 95 percent of the people who inhabit our planet.