Many have said that the frequency and duration of standardized testing has increased, teaching to the test has increased. This becomes a kind of censorship as it fosters a belief that if it's not on the test students don't need to know it.
I'd argue that this has more to do with the politics around teacher evaluations than common core standards. Many states have decided that they "need" to use standardized test results to evaluate schools and individual teachers, and have linked money and job security of teachers to the results of the tests. Politicians want to reduce student learning to neat little numbers, and standardized tests make that easy. Our state (Washington) is in trouble with the feds this year for NOT trying teacher evaluations to standardized testing. (
http://www.huffingtonpost.com/2014/04/24/washington-no-child-left-_n_5207245.html)
