"All Dried Up" is the seventh episode of season one of the animated children's series The Magic School Bus. It originally aired on October 22nd, 1994.
Seeing that their class diorama is void of animals, Phoebe asks Ms. Frizzle if they can add them. Carlos questions Phoebe over whether those animals could survive the desert heat. She is driven to the point that she feels they need to intervene and help the animals. She forms Students Against Desert Scarcity (or "S.A.D.S."), and by the suggestion of Arnold (who has a Field Trip Survival Guide), she asks Ms. Frizzle if they can go to the desert to help the animals. While flying over the mountains, she asks if they're going in the right direction, which prompts Carlos to explain the rain shadow effect, in which the mountains get the rain, leaving the lands on the other side dry. After seeing how various animals protect themselves from predators and the heat, Phoebe is still convinced the animals need her to bring them water. A rainstorm moves in and floods the desert, Phoebe and Carlos getting to the bus in time. The following morning, the desert is in full bloom, and Phoebe realizes the animals didn't need her after all.
While the class is making a desert for their diorama, Tim feels that something is missing. When Phoebe finally concludes that the diorama is missing desert animals, she asks Ms. Frizzle if the class could add them. So Ms. Frizzle gives Phoebe a model of a kangaroo rat and a Gila monster. Phoebe also adds in a tortoise, beetle, scorpion, jack rabbit, roadrunner, and a coyote, much to Liz's discomfort. Carlos, however, is dubious of all these animals surviving in the desert due to its extremely high temperature and lack of refuge. So Phoebe decides to do something about this. To the class' surprise, Arnold decides that they should take a field trip to the desert. Phoebe endorses Arnold's recourse, forming the acronym S.A.D.S. (Students Against Desert Scarcity), and Arnold tells Ms. Frizzle that he is prepared for the field trip, for he has his Field Trip Survival Guide with him.
So the class hop onto the bus and ride to the desert. When Phoebe asks Ms. Frizzle to speed up the vehicle, Ms. Frizzle transforms the bus into a biplane, and it flies away. When Phoebe notices that the bus is flying over the mountains, she tries to tell Ms. Frizzle that the bus is going the wrong way. But Ms. Frizzle elucidates that the desert wouldn't exist if there were no mountains. Carlos supports Ms. Frizzle's argument and explains to the rest of the students that some mountains have what is called the "rain shadow effect", which is the condition of water vapors condensing into rain or snow once warm, moist air rises above the mountain. So since the mountains catch all of the moisture, the air is able to reach through the other side, thus making it dry as the desert. When Phoebe gets overly inquisitive, Ms. Frizzle reminds her that she'll find an answer. The teacher lands the bus safely onto the dry land of the desert and the class exit the bus. They are appalled of the condition of the desert and they come across an animal known as the collared lizard, as well as the roadrunner, who is attempting to eat the lizard as its lunch. Phoebe tells the class that they need to protect the lizard and to her surprise, the lizard manages to get away on its hind legs. So Phoebe and the rest of the class hop onto the bus, which Ms. Frizzle transforms into a Gila monster. The roadrunner then proceeds to chase after them.
As the roadrunner continues to chase the bus, Arnold reads a cryptic tip in the guide that in order to avoid being eaten, one must become inedible. So Ms. Frizzle transforms the bus into a horn lizard, which prompts the roadrunner to walk away. The bus transforms back to its normal size and continues to ride. The class then exits the bus to search for animals in deference to Phoebe and become tired, hot, and thirsty. When Phoebe notices a jack rabbit alone, Arnold reads the next tip of his guide, which says that to avoid the heat, wear a hat. So Phoebe proceeds to take Arnold's hat and attempts to put it on the jack rabbit, only for it to hop away. Ms. Frizzle tells her that jack rabbits have ear conditioning. Dorothy Ann explains how a car's radiator cools off hot water from the engine and juxtaposes it to the jack rabbits' ears which do the same thing. So the jack rabbit stays cool due to the blood running up its ears.
As evening falls, Phoebe notices a tortoise walking by and tells the others that they have to help it. When Phoebe asks Carlos, "How would you like to be a tortoise resting in a hot, desert sun?", this prompts Ms. Frizzle to transform the bus into a tortoise. The bus follows the tortoise to the tortoise's burrow, which is its shelter. Phoebe then tries to convince the class that the reason they didn't see every desert animal is because they had already burnt up before the class' arrival to the desert. Just then, another tortoise pushes the bus out of the burrow and outside the night-sky desert. The class then notices a coyote howling to the moon, as well as other different desert animals. Phoebe then approaches a scorpion and its progeny, and Carlos elucidates that the desert animals were just waiting for the sun to go down before coming outside. Phoebe, while acknowledging her mistakes, decides to give water to the animals by herself. Carlos tries to convince Phoebe that there's a way that animals can get water somehow. When Phoebe asks him exactly how, a dark storm cloud hovers overhead, and rain falls. The class quickly enter the bus just in time for a sweep of water flowing their way.
The next morning, the class wake up to find a prolific amount of plants around the desert. They notice shrimp in the puddle and peccary, a desert relative of pigs, eating cacti, which are replete with water inside. Phoebe finally concedes that the animals don't need anyone's help to survive in the desert, for they have enough adaptation to beat the blazing heat.
As the students leave via bus, Arnold reads another tip in the guide: "For those without desert adaptations, always travel with a teacher with frizzy, red hair." Ms. Frizzle transforms the bus into a biplane and the students return to class. Despite already knowing about the desert adaptations the animals have, Phoebe still thinks that there are animals in need of assistance, calling herself and the rest of the class S.A.S.H. (Students Assisting Sleepy Heads), for Carlos, who is still sleeping on the bus. Dorothy Ann then tells Phoebe that hibernation is an adaptation. The class leaves with laughter, and Ms. Frizzle tells them, "If you can't take the heat, get out of the desert".
- Instead of the producer answering the phone at the end, it's Phoebe. She's the only one of the students to be featured during the phone segment.
- This is the first episode Ralphie is seen without his cap.
- The TV tie-in book was called "Gets All Dried Up".