I disagree with the alpha advice above. My credentials are only 25 years of owning and training gsds and other dogs (including fosters and adopted dogs with serious behavioral issues). I used the alpha roll on my first dog b/c I didn't know any better. However, it was a really crappy way to train and made no sense at all to my dog. In fact, it made her think I was unfair and unpredictable--not a good way to establish leadership. Unlike what is written above, physically forcing your dog to roll onto their back can encourage, instead of discourage, aggression. It can destroy your dog's trust in you as a fair and consistent leader. This method of training is outdated and never made real sense.If you study pack behaviour its a natural course.when i was learning to become a zoologist my animal of choice to study in my course was the wolf.gsd's tend to have more wolf characteristics than most up with mals and huskys.you should only assert the back roll when it requires it and not use it for every little thing.only serious issues.generally aggression. Tell them no or whatever your command is and then make sure you use consistencey.if need be use the roll.why should the roll be dangerous though?well handled puppies should have this down pat from an early age and be confident and happy with the handler even with the roll in use.it doesn't hurt them just lets them know when they've pushed their limits to far and corrects them before they develope a bad habit.prevention is far better than correction after its learned.you should always be the alpha along with your kids and husband.it natural heiarchy and for the safety of the family that lives with the dog.but to each his own.and whatever works for one may not work for another.
Wolves don't actually roll other dogs on their backs. The dog who is rolling is submitting to the other dog so the rolling dog is actually offering the behavior to show that they are submissive. I have read and seen a lot of examples of the so-called "alpha roll" in dogs and in wolves and in every case the dog is voluntarily rolling themself. The other dog/wolf never grabs the other dog and forces then down and over.
Here is an example of one dog alpha rolling the other with a written explanation from a trainer:
K-9 Solutions Dog Training, Inc.: An alpha roll on video
And here's Dr. Patricia McConnell, who is a prof at UW-Madison in Zoology, talking about "dominance."
The Concept Formerly Described as “Dominance” TheOtherEndoftheLeash
The best way to discourage nipping and biting is to constantly redirect your dog to a desirable activity like chasing a ball or toy or chewing on a toy. I substitute my body part for a toy and praise like crazy when they take the toy. This method usually works pretty quickly and you will find that your puppy will start automatically grabbing a toy when excited.
My most recent example is Rafi. I adopted him at age 1.5 and he was wired for sound! When he would get excited he would leap straight into the air and snap in my face, or he would grab a hold of his leash and engage me in a game of tug while we walked down the sidewalk. I taught him to put toys in his mouth when he was excited and now he carries a toy with him everywhere in the house and a ball on every single walk. No more leaping and snapping and no more leash tug of war.