I just got a puppy and he likes to bite. I know that's how puppies play but he's starting to mouth on the kids. I want to curb this behavior so he doesn't think it's ok. I've tried all the tips, yelping to let him know it hurts, growling and showing my teeth so he knows I'm alpha and he just thinks it's play time. Is there something else I can try to get him to stop mouthing?