Trigger is our mini-rex therapy bunny.  He has always been a favorite w/ all the kids and he has a really wild and crazy personality.  Lately he's gotten really mean.  He's been biting and lunging at staff and sometimes the kids.  He especially does this when he is caged.  I attempted to feed him and give him some carrots and he bit my finger so hard it was bleeding profusely.

I know that one of the probs is he really needs to be neutered....we are still trying to put the funds together for this.  I'm attempting to convince my supervisor to just bite the bullet and pay out of pocket.  Also, last month, Shelli, his bunny staffer left for maternity leave.  He had a special connection w/ her and spent a great deal of time hanging out under her desk.

Lately (possibly b/c Shelli's careful eyes aren't present) he's been escaping his room and attempts to sneak into the other classrooms.  He's VERY active and needs his daily exercise, but b/c the staffing is low in his room, I'm afraid he's not getting the exercise he needs.

I believe I've answered this all myself, but I'd love some input.  I just don't want him to attack any of the kids.

Since you are still working on getting him neutered, you can maybe try redirecting his aggression.  Has he tried to get toooo friendly with people (if ya know what I mean...hubbahubba  ?  If so is aggression could also be due to sexual frustration.  You could get him a bunny buddy toy bunny.   He could work out all his moods on that.    Be sure to get a toy bunny where the fibers don't easily come out as he will most likely groom it.  Also, if he starts chewing it up and "eating" the toy, then you'll have to take it  away. 

IF the kids offer greens, like parsley, mint, rosemary etc, will he bite their hands? 

I agree with Binky Bunny. He needs a stuffed animal to love if you know what we mean. Give him a digging box or a blanket to arrange or another toy like that that will take energy for him to use. He needs to work off some energy. I think neutering him will definitely alter the agression that he is currently showing.