1. The practicing is basically just "principal calls your name, you walk across stage, pretend to receive diploma, shake with the right hand", right?
2. If the principal were to mess up someone's name, hopefully that person would correct them before the big day, right?
3. Are there dress rehearsals for graduation? I remember the seniors at my school got their robes a week or so before their practicing days (of which there were three).
4. Is it bad luck to be in your robes before the ceremony?
Edit: I think I have enough info to work with now. Thanks very much!