You mean 3A by AAA, then that is your high school classification. Your high school's level (1A and up) is usually determined by area or population. This is used in sports to determine what teams are in your conference (teams that you face in your area), region (schools that you face that have to the same classification as your school, but are too far away for efficient travel) and state (teams that you face from around your state that have your classification). Some sports in your school may have different classifications based on who they want to face.