stealing food

Question
our golden retriever,Teddy, is 1 yrs old,neutered , went 2 trainning classes at petsmart, he stays and sleeps in our kitchen when no one at home or at night; he is an inside dog. Our kitchen is a confined area so it just like his big crate. We are feeding him dog food from Nutro . We tried to walk him about 40 mins a day, but sometimes will miss a day or 2. we have about 10 dog toys for him. My children play him all time when they are home.
The problem is he steals food, when we have any food on the table and not watch, he will take it. I say NO to him and from his expression, he knows I am not happy about it. My children sometimes give him food when they are eating . I keep telling them not to. They are improving. Besides food, he loves to steal the paper on the table , he will either eat it up or tear it apart. Please advice what to do. What is the efficient way to train him "leave it"? The way we do is to leave a paper towel which he likes to destroy on the floor and tell him leave it, when he doesn't touch it, we give him treat. When we are training him, he won't touch the paper towel , but when it is over, he eventually will come back to tear up the  paper.  I can't wait to receive your help and tips. Thanks! karen

Answer
Karen, kids are unreliable when it comes to this. The best thing to do is to remove the dog from the kitchen (or whatever area the kids are in) when they are eating, so that there is no possible way for them to feed him from their plates.

The other thing you need to do is to keep food and paper off the tables and counters for a while. Remove the temptations completely, and the behaviors should extinguish themselves because he will not be continually rewarded. It's not going to happen overnight, though. It will take a month or two before he really stops 'checking' the countertops and tables. If, at any time, he is rewarded by finding a piece of paper or food on the counter or table, you have to start all over again and it's going to take that much longer to fix.