https://tfpstudentaction.org/blog/9-reasons-why-common-core-is-bad-for-education

Prof. James Milgram of Stanford University was the only Mathematics expert involved in developing Common Core. He refused to sign off on the Common Core Math standards when he saw how inferior they were to existing Math standards. He pointed out that Common Core Math delays Algebra I until 9th grade and does not include Calculus in high school at all, which are necessary for students to be prepared for STEM courses in college. Prof. Milgram concluded that Common Core will put American students at least two years behind the high-achieving countries of Europe and Asia.

Jason Zimba, the main architect of Common Core Math, admitted that it will only prepare students for Math courses at a non-selective Community College, not a four-year university.