Jack russell is nipping my kids, 9 weeks old

Question
We just got out new little jack russell about a week ago. she was 8 weeks when we got her. I have a 3yr old and a 7yr old.
For the first few days we had the puppy she was awesome. she has potty trained easily and is already sleeping through the night. when we got the puppy she first took to my son who is 7yrs old first. so i would say that adopted him first in our family of 4. before we got the puppy we talked with the kids and made the rule that no one picks up the puppy other then adults. the puppy has never been left unattended with the children because i want to make sure that when they play with the puppy they are playing properly and not picking her up or being rough. so far the kids have been awesome with the puppy and the puppy was awesome with them. if the kids were on the floor the puppy would come up and sit on their laps and fall asleep for a long period of time. but the last couple of days the puppy has started to nip both of the kids. she has tried with me and my husband but not nearly as often as she does with our children. they want to play with her but she is more focused on jumping on them and biting their hands, feet and clothing. i do believe this is all in play because she isnt barking or grawling when she is doing this. it just seems as though she has replaced them for the chew toys. also, when the kids get out of bed in the morning she is most excited to see them. so she isnt fearing them in any way. I have been trying to encourage the children to tell her NO firmly and give her one of her own toys to play with.. try tossing her ball and change the game.. but she isnt interested. but when im on the floor she really enjoys playing fetch with me. Do you have any suggestions?? I dont want her to dominate them in any way. Please help! Jen

Answer
Hi Jen,
You're doing the right thing by telling them to immediately say NO, and it's also good that you're teaching them to give her a chew toy instead. Another good trick that works is have the kids immediately stop playing with the puppy and walking away, thus sending a message that they will not play if she is going to hurt them.  All of these techniques are good and will eventually work but puppies take a long time to learn and the training has to remain consistent. Every family member should use the same command. Your 7 year old is old enough to understand and teach the puppy but 3 years old is really too young to really understand so you're going to have to keep a close eye out when she/he is playing with the puppy. Those little teeth are very sharp, but luckily the actual bite doesn't have much force. I don't suggest anyone take one of my puppies unless the child is 5 or older. It's going to be hard on you for a little while.  
Be prepared for constant chewing on anything and everything that she can get her mouth on. This is a big teething time and will remain so for a good few months! Keep plenty of natural rawhide and other safe things around that she can chew and correct her with a "NO BITE" command on the things she is not supposed to chew on... like little fingers and toes. Have patience it's going to take a while for this stage to pass, but it will eventually pass once those baby teeth fall out and the big ones come down.
You're doing a great job, keep up the good work.