Starting on Sunday, rather than letting Foreman out the glass door to the deck, I walked him over to the doggy door and pushed his nose through it. The first time he put on the brakes and then gave in and darted through the door. He stood on the deck looking in at me as if he was terribly insulted.
Tonight I got home and let him out of his play cage and he ran to the door to go outside. I walked to the doggy door and he darted right through the door outside, danced around on the deck, ran back inside, then back outside, and did his thing in the yard. He seemed surprised that the same door could lead to two different places. No trauma or whimpering. He seems to be learning where the little door leads.