Adult High School Diploma: The Adult High School Diploma Program offers classes to earn credits to complete adult high school requirements and earn a diploma. Students must be ages 16 and older and live or work in N.H to register for an Adult Diploma class. We offer three terms: fall, winter/spring, and summer. ABE/HiSET: This class is for students ages 18 and older who want a review of basic reading or math skills or who would like to prepare for the reading, writing, social studies, science and math portions of the High School Equivalency Exam (HiSET).