Panel 1: A little while later, we see John and Liz looking up at the tree in the back yard. As he starts to put the ladder away, he tells her "There we are.....two birdhouses side by side."
Panel 2: When she gets all gloomy about how his is better, John attempts to reassure her by saying that they're both good homes.
Panel 3: We find them in the garage actually putting the ladder away and explaining to her that birds don't know the difference anyway and won't even know that she built the one she built. Rather than ask him "Then why did you make me feel like a garbage person by building yours in such a manner that I couldn't possibly be expected to follow", Liz sets up the sitcom punchline by insisting that they will.
Panel 4: Since he forgets that he's in a domcom from the fifties, he's shocked when Liz says that she put her name on it.
Summary: The teaching moment has been thoroughly squandered. Now, to the depressing denouement of Elly getting to nail her stupid ass to her cross.