To the uninformed, confining dog training lessons to a crate may seem cruel. However, from a dog's perspective, a crate can be his den, his own little corner of the world reserved exclusively for him. For the owner a crate can make training a puppy or grown dog a much simpler task. So long as you follow a few guidelines for crate training, your dog's crate will feel like his castle and your castle will be safe from the ravages of an untrained dog.

http://www.youtube.com/watch?v=9vlXqT13AVc