Training your dog to obey in real life
Relevancy is the key to having a dog continue to obey long after class is over. Dogs usually learn things in context and if not trained under any circumstance will not obey in any circumstance. For instance it's great if your dog sits, downs and stays in the kitchen, but not very helpful if he won't do these things when you need him to elsewhere. The key to making the dog obey in all circumstances is to show him how his training is relevant to real life.
The first step is to make a list of what your dog finds enjoyable. Your list might include dinner, playing with other dogs, being let out in the yard, going for a walk. Instead of these pleasures simply being given to the dog, make him earn them by asking him to do something before they happen. For instance ask your dog to sit, before dinner goes on the floor: don't repeat yourself over and over, if he doesn't sit, you walk away with the bowl and come back in 5 minutes to try again. If your dog wants to go out to the yard to play, ask for a down before the door is opened. If he doesn't lie down you walk away and try again later. Pretty soon your dog starts paying really close attention to you and what your asking, realizing for the first time that those things he learned in doggy school are indeed good for something. If you don't make things relevant for the dog and don't teach him how to use his training you will have an unreliable and inconsistent dog.
Think of when you were in school learning geometry. Didn't you wonder what the heck any of this had to do with what you wanted to do ? Well, so does your dog !! Class was great mom, but what's it got to do with playing ball, dinner and a nap ? Make your dog's training real for him and you'll reap the rewards of a well behaved reliable companion.