Funny teacher and pupil math jokes

Teacher: What's 2 and 2?
Pupil: 4.
Teacher: That's good.
Pupil: Good ?, that's perfect !
 
Teacher: If 1+1=2 and 2+2=4, what is 4+4 ?
Pupil: That's not fair; you answer the easy ones and leave us with the hard one !
 
 
Teacher: Now class, whatever I ask, I want you to all answer at once. How much is six plus 4 ?
Class: At once !
 
If there are ten cats in a boat and one jumps out, how many are left ?
None; they were all copycats !