The term K THRU 12 is a shorthand way of saying 'from K to 12, ' which is a reference to the American educational system. The crossword solution ELHI is an abbreviation for the term 'elementary, middle, and high school, ' which are the three levels of education in the United States. Therefore, the crossword solution ELHI for the term K THRU 12 is referring to the educational system in the United States, from kindergarten (K) to twelfth grade (12).