Caroline finds out that Max never actually graduated from high school because she failed to show up for a single history exam.
Caroline hopes the occasion will help Max reconnect with her estranged mother. She invites Max's mother to the graduation ceremony, but her mother ultimately fails to show up. [S3E24] And The First Degree
Determined to change this, Caroline convinces Max to study and travel back to her hometown so she can take the final test and earn her degree. Caroline finds out that Max never actually graduated