Oh, good for him! He's adorable and you absolutely should be proud of his quick learning skills!

We are going to have to employ the same technique once we move. Right now, the dogs have free access to outside through a dog door into a fenced part of our yard. In the new house, we will be without such a door so the puppy will have to learn to alert us. The old dogs know how to ask for what they want (hopefully, they'll remember!) but Sara is used to just following their lead or doing whatever she wants. She drinks and pees way more than they do too, so it'll be interesting.