My Jack Russell and my 3 yr old son

Question
I have a male Jack that will be 6 in March and my son will be 4 in March.  My son is a typical mischievous boy and he is always chasing our dog or pretending to shoot him - just irritating him to no end.  My dog bares his teeth and gets nervous around my son because he never knows what he will do.  We have punished our son and talked to him at great length about why what he is doing to the dog is wrong and how he will get hurt but he just doesn't seem to get it.  My dog bit my son's finger pretty bad and now I am worried - will next time be worse?  Should  we find our dog a new home without small children?

Answer
Three year old kids just DON'T get it, which is why I never sell a puppy to a household with kids under six.  There is a great possibility that the bite will be worse next time!!! It's so not fair to the dog who you've had for 6 years, but you obviously can't get rid of your child! As much as I hate to say it, you have to seriously consider placing the poor dog somewhere else for the safety of your little boy. Maybe a family member can "hold" him for you for a couple of years until your little guy understands the risks.
Sorry you have to make this decision, best of luck.