"As I always say, no guts, no digestion!"
- Ms. Frizzle
"For Lunch" is the second episode of season one of the animated children's series The Magic School Bus. It originally aired on September 17th, 1994.
In the opening scene, Arnold is seen chewing gum, trying to break the school's gum chewing record, and anticipating to win two free tickets to a ride called Action Mountain, the ride of Wanda's dreams. Dorothy Ann, on the other hand, isn't too impressed, as she is more focused on the assignment issued by Ms. Frizzle regarding digestion. Ms. Frizzle suddenly enters the classroom while playing a tug-of-war game with Liz. Liz lets the other end go, and the rope slithers inside the skeleton and inflates into a model digestive system.
Ms. Frizzle gives the class an encouraging statement stating "no guts, no digestion!" Wanda adopts this phrase on her anticipation to get the tickets on Arnold winning the record contest, while excitedly slapping him on the back. Upon realizing that this careless action resulted in Arnold accidentally swallowing the gum, she is deeply disappointed, but sincerely forgives Arnold. However, when Ms. Frizzle announces a field trip, Wanda is once again thrilled, while Arnold falls into further dismay.
As the class boards the bus, an anxious Arnold states that he is very uncomfortable after inadvertently ruining Wanda's day and fears that he could accidentally ruin the day of the entire class. Ms. Frizzle decides to allow him to volunteer out of the field trip, much to Arnold's surprise, with Liz as his substitute teacher. He contentedly agrees, yet he develops a suspicion due to the fact that Ms. Frizzle has never actually allowed this before.
As Arnold turns away, opening a bag of Cheezie Weezies for a snack, what he does not know is that the bus has ambiguously shrunk in size and is heading his way. The tiny bus, blending perfectly in with the Cheezie Weezies, is consumed by Arnold without knowing it in a handful. Ms. Frizzle then drives across his tongue, where the class observes "the pink pavement," "dripping walls," and the "humongo white things," but are all disgusted upon realizing that they are in a person's mouth. They become even more stunned when Ms. Frizzle presents them with a digestive diagram, revealing that the body that they are entering is Arnold's. After eating the Cheezie Weezies, Arnold heads back to the classroom but has feeling of emptiness in the classroom. Unaware of the class's location, he grimly states that now he is no longer an obstacle for them anymore. He notices a jar of olives, picks one out, and chews it, still not knowing that the class is observing the first step of digestion right in his mouth (grinding food into smaller particles). Swallowing the olive, he takes the bus along with it.
The bus is brought down Arnold's throat and into his esophagus (which automatically pushes the bus down through it) and out into his stomach. While it begins sailing on the surface of the stomach acids and food particles in there, Arnold has already finished consuming the entire jar of olives, thinking of a plan to break the school's olive eating record and reclaiming Wanda's respect. His hope is short-lived when Liz tosses the school's record book to him, showing that the highest record was 978 olives - too long a way to go.
While Arnold looks through the book for other unbroken school records, his stomach muscles are beginning to contract, generating turbulence motions in the content and on board the bus. The class also observes the wad of gum, which they initially mistake for a giant rock. They also get a feeling that the bus is dissolving due to contents other than just food and water, and their fear is confirmed after Ms. Frizzle calmly states that it's the presence of hydrochloric acid (stomach acid). The film then jumps to a cut scene, where Dorothy Ann presents a flow chart presentation for the digestion they've endured, while in industrial attire at a "digesting" enterprise she says is called United Digestion.
The scene then cuts back to the present, where Wanda is amazingly impressed by what they'd witnessed in the scene of Arnold's digestion. She is so amazed that she says that Arnold "doesn't mess around when it comes to digestion". When Ms. Frizzle states that they had not seen anything yet, Wanda cheers even more for Arnold. This only causes more nausea to Ralphie, who was already suffering from motion sickness. Outside, Arnold miserably fails to break the record of placing the most pens in a shirt pocket one by one, as it inevitably expands and bursts out.
The bus transforms into a submarine and enters Arnold's small intestine, along with the food remnants and the undigested gum, an object in which Ms. Frizzle states is too tough to be broken down. Inside the small intestine, the students observes countless numbers of "rubber cactus-like things" called villi, via scuba diving in Arnold's digestive juices. While Tim wonders where the nutrition is redirected from it, the film jumps to yet another cut scene. Dorothy Ann narrates that after nutrients are sucked out of the digestive tract, they are sent into the blood stream, which then transports the nutrients system wide. The scene cuts back to the class realizing the function of the villi, but their attention is disrupted after Wanda gets separated from the class and caught on the gum that is rolling away.
In the classroom, Arnold fails again at another attempt to break a school record by napping, waking up two minutes and four seconds short. He fails to see how he can break this record if his stomach keeps waking him up. As the class tries to rescue Wanda, they exit Arnold's small intestine and up in the large intestine, where the atmosphere possesses a dry, but rather, odorous environment. As they move on in search of Wanda, food particles surrounding them grow drier and drier as they progress deeper. When they finally catch up with Wanda, she and the gum are both hanging precariously on a ledge. Struggling to keep her balance, Wanda loses her balance and falls off, but is saved after one of her feet attaches to a strand, which acts like a bungee cord, and propels her back up and into the bus where Carlos grabs her and pulls her back into the bus. However, due to the class' misunderstanding, she is not in peril, but rather enjoying a treacherous "thrill ride" through Arnold's digestive system.
When Ms. Frizzle states that the trip is not over yet, Ralphie becomes frustrated, reciting all the organs of the digestive system consecutively and asking what's left to go through. Ms. Frizzle answers that they just need to "join the rest of the waste products and finish the trip." With the shocked and disgusted class realizing what that really means and refusing to do so, they plan to exit out of him by going back the way they came.
Outside, a seemingly hungry Arnold is anxiously digging out of a locker, stating his inability to break the lunch eating record when he is unable to find lunch. However, reaching into Ralphie's lunch, he manages to obtain a Chocolate Mallow Blaster with delight.
Meanwhile, Ms. Frizzle's class is busily propelling against the digestive cycle, but they are troubled after realizing the difficulty of departing from the stomach. While they are frustrated, Arnold is also in a state of unease; he knows that breaking the lunch eating record will help him regain Wanda's respect for him, but he will also anger Ralphie by stealing his lunch. Suddenly, a slow, misty voice speaks his name the instance he is about to take a bite of Ralphie's Mallow Blaster. The voice, disguised as his "conscience", is actually Wanda speaking on the bus microphone. She then coaxes Arnold into drinking the bottle of seltzer in her lunch, which makes him hesitate at first and become suspicious of his "conscience". Wanda, on a short fuse, snaps at him to just drink her seltzer, and seeking this as another opportunity to break a school record, he does so after telling Liz to time him.
When the seltzer enters Arnold's stomach, the class begins rocking the bus back and forth to create a giant gas bubble in the content. One forms, which carries the bus afloat and up the esophagus. Arnold loudly belches, without knowing that the bus is propelled out of his mouth by the force. He is yet again disappointed when Liz tells him that he failed to break the seltzer drinking record. His disappointment is interrupted when the class and Ms. Frizzle return to the classroom, carrying a tray of lunch for him.
While Arnold eats a hearty meal, Wanda presents him with a trophy for "breaking the record for being the best field trip ever". When Arnold asks the class where they went, they tell him that they had literally gone inside him. Unsettled at this, Arnold declares that in the future, he'll always participate in all future field trips. But his courage is once again thwarted upon realizing his next destination, while the class laughs out loud.
- Tim's drawing of Arnold's digestive system includes the large intestine before the class even visits or knows about it.
- Arnold breaks the fourth wall in the end when he declares that he is willing to participate in all the following field trips, but he is discouraged upon seeing the dinosaur on Ms. Frizzle's dress, to which he says, "...starting right after the next one." However, when the class does go back in time to see dinosaurs in "The Busasaurus," Arnold ends up going with them and becomes the hero of the field trip.
- Arnold swallows the bus again in "Goes Cellular."
- Phoebe talks about her old school for the first time, having not done so in "Gets Lost in Space.
- This is the first time the bus shrinks without Liz and Arnold.
- In the producer segment, the clip where the bus is a digestive submarine (Small Intestine) swimming through Arnold's stomach, that was never shown in or during the show.
- Despite the fact that the bus is inside Arnold's body, he is seen riding in the back twice. A similar error happened in "Revving Up".
- The kids are in their regular clothes during the scenes where the bus arrives back in the stomach.