3 year old boy oppositional esp. at school

[meladramamama]

My youngest son is 3 - his older brothers are 7 and 5.  He is very loving and cuddly at home.  However, is also very agressive and oppositional, especially at school.  I understand the typical 3 year old behavior of wanting to assert oneself, but he has tried to bite his teacher and has said things like "I will get a sword and cut you."  He was moved out of his original preschool class b/c he was biting and hitting another boy (who was also equally agressive).  So far, his behavior toward his friends has improved, but toward the teacher it hasn't.  The teacher seems to understand that he is testing her and she's not worried.  However, I am becoming very concerned.  I'm not sure how much of this is normal.  My other two boys did not act like this school (but they are all very rough at home).  Is he just not ready for school?  He says he wants to be good, but it's hard.  He attends a catholic school 3 days a week from 8 - 2:45 pm.  Is that too long of a day?  He was also aggressive in his 2 year old program (2 days a week for 3 hours).

[meladramamama]

Other than his brothers, he doesn't really have friends outside of school.  I've volunteered in the classroom.  It seems most of the other children sit quietly at circle time and he would rather be doing his own thing.  He is a big boy (much bigger than his brothers were at his age) and he doesn't seem to realize how much space he's taking up.  He is always defiant.  His oldest brother is/was the same, but too scared to act out at school.  My little guy isn't scared of anybody - not even the nuns.  Of course, he's learned words/actions from his older brothers, but his behavior goes beyond that.  It seems he gets really angry when he doesn't get what he wants.  That seems to be the heart of the problem.  I'm not sure if it's best to try to nip this in the bud with a teacher who seems to have experience with this or if it's a case of him truly not being ready to be in a school environment.

[specialmom]

Hm, it is hard to say with his age what is going on.  My child struggled in preschool at 3 but in slightly different ways.  How is your son's focas during circle time or doing an activity?  Some kids have trouble with new and stimulating enviroments-----  does he have any trouble anywhere else?  Does he have friends outside of preschool that you've seen how he plays?  

Could you volunteer in the room and see what you think the problem is?