Helen and Martha come to visit T.D., but he's looking a bit glum. When Helen asks what's wrong, he explains that (although it's Saturday), he doesn't want to go back to school on Monday. Helen asks what's so bad about school, and T.D. explains that on Monday his math homework flew out the bus window, on Tuesday a boy named Alvin Murple sat on his (T.D.'s) lunch, on Wednesday he got locked in the utility closet, on Thursday Alvin accidentally knocked over another boy, Billy Snyder, who fell onto T.D.'s lunch, and yesterday, he got distracted during science class and was assigned to invent a project come Monday.
He says he wishes he were a dog, since he thinks they have it easy due to no school, but Martha disagrees, so they decide to "try being [each other] for a day". T.D. decides to be a dog the next day, while Martha decides to be a human on Monday. Later that day, O.G. tells T.D. what he needs to be a dog, while Helen tells Martha what she needs to be a human. Even though they have to go without drawing or chasing squirrels respectively, they think it will be easy.
The next day, Martha shows up at the Kennelly house, and O.G. has built T.D. a robotic tail. However, he can't wear it as it doesn't work. After eating alphabet soup messily from a bowl, T.D. plays with Martha and her dog friends at a park and enjoys himself. He then wants to invite Helen and Truman over, but they're busy with chores.
He wants to shelter from the rain with Martha at the library, but dogs aren't allowed there, so they shelter under his porch. Despite being disappointed to learn dogs don't eat lunch, he still enjoys being a dog. However, when the rain stops and they come in, it's already dinner time. T.D. isn't allowed to open the fridge, since dogs don't, but when he yells that he's hungry, O.G. gives him another bowl of soup.
While he would have preferred something different for a change, when Helen comes over, he thinks being a dog is still better than going to school. O.G. finishes the robotic tail and attaches it to the back of T.D.'s pants, but it comes off and flies out the window. That evening, he misses drawing and sleeps in a doggie bed.
The next day, Martha goes to school to try to be human, but embarrasses T.D. because she knew the capital of South Dakota but he didn't. When Martha enjoys her lunch, T.D. complains that it seems to be easier for her to be a human than him to be a dog. Martha, however, assures him that there have been hard aspects of being a human too, namely that she had to wake up early. T.D. then realises that he still has the science project he needs to submit, but Martha decides he can use the thing he did with being a dog. So, he does, and he concludes that being a dog is not easier than being a human, nor is it harder, but both are easier with friends.
This episode provides examples of
- Alliterative Title: Dog for a Day.
- Asleep in Class: Discussed when Martha complains that you're not allowed to sleep in class.
- Bizarre Beverage Use: According to O.G., when he was ten, he surmised he could fuel a go-kart with root beer, and that it may have worked had he not gotten thirsty.
- Comically Missing the Point: When O.G. says, "I have it!", T.D. replies, "What?", and O.G. says, "A tail!" (meaning that he'll make one for T.D.) T.D. replies, "You have a tail!?".
- Continuity Nod: When Helen mentions that most humans either work or go to school, Martha says she was a substitute teacher once. This happened in "Martha Goes to School".
- Dogs Hate Squirrels:
- Martha is seen chasing a squirrel in front of the Kennelly house.
- She then growls at another one, before Helen tells her she must not do that if she is to be human.
- Ear Ache: Downplayed. It's a bit painful when T.D. tries to scratch his ear with his foot.
- Early Personality Signs: O.G. apparently tried powering a go-kart with root beer when he was ten, meaning he's been a wacky inventor for quite some time.
- Flashback: We see scenes from the previous week when T.D. is explaining why he doesn't want to go to school.
- Is It Something You Eat?: When Martha first hears the word "results", she assumes they're a type of food.
- No Animals Allowed:
- Discussed when Martha thinks the worst words in the English language are "no dogs allowed".
- Dogs are banned from the library.
- Non Sequitur: When T.D. wasn't paying attention in science class, Mrs. Clusky asks what the conclusion is, so he says, "Um, toothpaste?".
- Scary Science Words: When O.G. says that T.D. has an unusual "hypothesis", T.D. nervously assumes that's a disease.
- Sleep Deprivation: Discussed. Martha claims she had to wake up early to memorise the state capitals and fell asleep in class, though she seems to have caught up on sleep by lunchtime.
- Speak in Unison: Both Martha and T.D. say, "This is gonna be easy!" at once in different houses.
- Split Screen: Martha and T.D. are shown on a split screen declaring that being another species will be easy.
- Unconventional Food Usage: Mrs. Clusky teaches science by making a chemical reaction with baking soda and vinegar.
