about story betwen teacher and student

1, high school, a classmate in the class collective the game do lose, then on stage and said, below I give you sing a song in English, are older, but we are all very familiar with.
A scream, and then is the warm applause.
The students sing: cleared his throat, ABCDEFG...
2, the teacher: the classmates, and after a few days, you will leave school, but your ability... I see you or for the exam several certificate to do that, but in the society too much, you want to get the certificate of is what certificate?
Student: marriage certificate