10yo son not acting his age - causing problems at school

Pertinent back story: My son loves bunnies. I mean, bunnies, bunnies, bunnies, bunnies. 24x7 "oh, bunnies are SO CUTE!". Everything revolves around bunnies. We do not own a pet rabbit, but have scads of stuffed bunnies. Also, he is struggling with social situations and is small for his age - kids tease him that he's only a 2nd grader - to which he responds with breakdowns, further reinforcing with his classmates that he is immature for his age.Last night my son tells me that his teacher said he can bring a bunny to school, and occasionally he can have it to cuddle with. He claimed to have no idea why.I emailed his teacher and found out that he's having some problems at school that we were unaware of. To quote: "He has been really struggling throughout the day to complete work. When he has to write, it is the worst. He will cry, refuse to do work, complain, or throw a temper tantrum. This happens when he doesn't pay attention and then has to get work done, or is paired with someone he doesn't want to work with, and other situations he doesn't particularly enjoy."According to teacher, they have been struggling with something that will motivate him sufficiently, and well.... bunnies.My concern is that this will infantalize him further with his classmates and exacerbate the social problems he is having.I'm concerned on many levels -- what our early lack of parenting skills may still be revealing, right down to him beginning to shutdown and withdraw and where that may lead.I would love to hear your thoughts on how we can get him through this.Edit for clarification: son is a 4th grader, and just recently turned 10. He is one of the oldest in his class. via /r/Parenting http://ift.tt/2jyd94e