I recall that a American Government textbook I once had refered to Scalia, Thomas, and Rehnquist as "extreme conservatives", to O'Conner and Kennedy as "conservatives", and Breyer, Scouter, Stevens, and Ginsburg as "moderates."
Government school, like government journalism, is based on the premise of "objective truth" which is actually an illegitimate "Establishment." The First Amendment is deeply suspicious of "objective truth."