I need two symbols:

 * *Passed* the Lesson
 * *Mastered* the Lesson (earned maximum extra credit)

CRITERIA

 * Universal 
 * Clear that Mastered is "superior to Passed"


Maybe there's nothing better than what I've got.

What I've considered:

Top choice is Silver Star (passed) and Gold Star (Mastered)


![enter image description here][1]


  [1]: https://i.sstatic.net/wRK6B.png