U.S. History or Calculus BC, e.g.

APCLASS

Think of the high school courses that can earn you college credit before graduation—often marked by these two letters at the start.

This clue refers to advanced high school courses offered through the College Board's Advanced Placement (AP) program. "U.S. History" and "Calculus BC" are both examples of AP classes, so the answer is a shortened form combining "AP" with "CLASS." The abbreviation "AP" is widely recognized in U.S. education, making this a straightforward reference for anyone familiar with the program.