 Kids don't know any better. They might unintentionally challenge or hurt the dog. Also, teach your child how to pet a dog gently. And no hugging, squeezing, or pulling. I've seen small kids hitting a dog on the head thinking they're petting them, but they're not. Make sure your kids and you don't play tug-of-war with the dog. If the dog wins, he's going to see himself as dominant. And watch the dog closely for signs. If he doesn't want to be pet anymore, you'll see it. And remember, always be there to supervise the interaction.