HOW CAN WE SURE THAT OUR DOG DOES NOT NIP THE CHILDREN WHILE THEY ARE PLAYING?
Never leave your children with the dog unsupervised. They could tease him beyond his endurance or play hard game that causing the dog become over excited and perhaps could resulting in him nipping them.
Also learn your children to respect their pet, and how to handle, speak to and play with them correctly. Taking them together with you while in training or in obedience class is a great idea in this respect.