Some students taking the SAT college-entrance exam Saturday had extra time to complete a section of the test because of a misprint in an instruction guide, at least briefly calling into question the validity of scores for nearly half a million test-takers. Shortly before noon EDT on Saturday, the Educational Testing Service, which administers the SAT on behalf of the College Board, notified the test maker that there was a printing error in the test booklets distributed to students in the U.S., according to a statement posted on the College Board website Sunday evening.