Diplomas, Caps, and Gowns
Graduation, the end of your school career.
At graduation everyone is excited to walk up to the podium and receive their diplomas. So when someone sees the rolled up paper with a ribbon tied around they think of this once and a lifetime event
The graduating students where mortarboards, the square hats, during the ceremony.
The long robes that are wore in graduations are a huge symbol. because they are so recognizable.