We have a 10 weeks old German shepherd. He likes to bite my three children, age 11, 9 & 7 on their feet and legs, often pretty hard, though didn't punch through the skin, but significant marks and scratches are seen. I have been interfering the biting by using the Bite Inhibition Games and training him by following the Biting, Mouthing and Nipping guide, as well as Take/Leave It and Drop It guide. None seems to work. He does not bite me though. He would sometimes come close to me, sniff a little or slightly drag on my pants, but doesn't bite. But when he sees the kids, he would run towards them and start biting. The kids then would move away their legs while saying 'ouch', but the puppy won't stop. I've tried to have the kids stay still without reaction, thinking not to stimulate the puppy more, but the bites are hard and really cause pain, the kids wouldn't be willing to try it again.
This biting problem really dramatically lowered the joy of having a GSD puppy in the family. The kids literally turned from excitement to frustration and terrified. I'm in urgent need of correcting this behavior.