Teacher: What are you writing?
Pupil: A letter to myself.
Teacher: Interesting. What does it say?
Pupil: Don't know. Won't get it till tomorrow.
Teacher: Where was Queen Elizabeth crowned?
Pupil: On her head. Duh!
Teacher: What do we call the outermost layer of a tree?
Pupil: Don't know.
Teacher: Bark, silly!
Pupil: Woof woof!
Teacher: Whatever I ask you, I want you to answer at once! Now, how much is 6+4?
Pupil: At once!
Any more?