When your child bites in preschool, first and foremost, you have to see what the age is. If he's two, the language development is not there, and when they're frustrated, usually they go to hitting and biting. So it's age appropriate. And what you need to do at that time is really redirect and talk about biting is not appropriate. If your child is older - 3 or 4 - biting is not acceptable, because the language should be there. And your child should know how to deal with his frustration by using his words and talking about it. And it's very important for you or the teachers in his school to really go through the process of why it is important that language should be used rather than biting. At the end of the day, most preschools will not allow a child to be in the preschool if he bites continuously, because there's something more than just the frustration, and he needs an outside help.