Our puppy kindergarten teacher told us to do what the mother would do-you take her down. This means that you gently but firmly put her on her side and hold her down by her head. This does not hurt (you shouldn't do it in a way that would hurt), but you should be firm and make sure that your puppy knows that she is not in control. This stopped ours from biting very quickly. They do grow out of it. Also you should be offering your baby something that is okay to chew.
