"Classroom Smarts" joke

TEACHER: How old were you on your last birthday?
STUDENT: Seven.
TEACHER: How old will you be on your next birthday?
STUDENT: Nine.
TEACHER: That's impossible.
STUDENT: No it isn't, teacher. I'm eight today.
***
TEACHER: George, go to the map and find North America.
GEORGE: Here it is!
TEACHER: Correct. Now, class, who discovered America?
CLASS: George!