Unfortunetly this happens from age two when this is their form of communication they cant explain themselves at this age that they happy, sad, glad, mad, angry, hurt ect and they do it out of reaction to what they feel the only way to channel it correctly is when you feel happy or proud with them hug them or kiss them show them you dont bite and then when the bite get them to bite into a block of soup and if that dont work use chillie sauce and some people say if that didnt work for them they would bite the child back to feel what if feels like and they will soon learn they cant bite. I remember going through this with my two year old last year there where atleast five biters in the class which can also make it difficult for your child if there are others doing the biting in class which us as parents must speak up and encourage our child care provider to help this situation to teach all the biters same lessons cant just be your child punished for bititing but all the other biters too should be punished as this age monkey see monkey do. Good luck all the best and remember youre a great parent