What is Common Core and why is everyone—right, left—so mad about it?

Or, as former George H.W. Bush Assistant Education Secretary Checker Finn likes to say: “Conservatives hate anything with the word ‘national’ in it, and liberals hate anything with the word ‘test.’ ”

The Common Core effort represents the latest in a long line of attempts to challenge American students, and to make the results of those challenges comparable among states and districts—efforts that have not been very successful in the past.

Source: Slate.