The term 'DIDN'T ACT' can be broken down into two crossword solutions: SAT (3 letters) and SATBY (5 letters). SAT is an acronym for the Scholastic Aptitude Test, which is a standardized test used by colleges and universities in the United States to assess a student's readiness for college-level work. SATBY is an acronym for the Scholastic Aptitude Test by Year, which is a version of the SAT that allows students to compare their scores to those of other students who took the test in the same year. Both of these tests are used to measure a student's academic aptitude and help determine their eligibility for college admission.