The First Question

The First Question 

One day after school the teacher says to his students, 

“ Tomorrow morning, if anyone of you can answer my first question, he or she can go home early. " 

The next day, when the teacher comes into the classroom, he finds the blackboard very dirty. 

He is very angry and asks, “ Who did it? Please stand up! ” 

“ It's me, " says Bob. “ Now, I can go home. Goodbye, sir! ”