The term GRADES 1 TO 12 can be summarized as the educational system in which students progress from grade 1 to grade 12. The crossword solution for this term is ELHI, which stands for elementary, high school, and intermediate. This is a common educational system in North America, where students attend elementary school from grades 1 to 8, high school from grades 9 to 12, and intermediate school from grades 7 to 8.