I got a puppy about 3 weeks ago (6 months old) from a family who didn't want him anymore. He's a great little guy, listens to commands pretty good, very affectionate, and is almost always underfoot. The family had kept him in the kitchen with pee pads (I can't stand the idea of pee pads on a regular basis....) So I decided to get rid of that habit right away (he was peeing a couple of times during the night....I couldn't let him corralled in another room because he cried). So the first thing I did was buy a crate, making sure to research the size etc, he peed in it once, and hasn't since so he seems to respond to that well. I treat him with treats when he peed outside and he stopped having accidents in the house(random places). So I know that he can hold it in, and I know that he understands going outside, but my issue is that if I don't see him go to the door he doesn't make any noise to let me know and so ends up peeing in front of the door. How do I train him to scratch or bark at the door or somehow signal the need?