Ralphie is crushed when a fever and sore throat keep him home from school the day he's scheduled to host a FNN (Frizzle News Network) television broadcast on health. Not one to let his body get the best of him, Ralphie hosts the show from his bed while his classmates journey through his bloodstream to reveal the news-breaking story of just what's making him sick.

It all starts when Ms. Frizzle's class is rehearsing Concerto for Invented Instrument. Carlos' invented instrument looks great, but sounds ploopy. Ms. Frizzle takes the kids to the Sound Museum - which is a spooky old house on a lonely hill, full of mysterious sounds. The children explore the Soundscape Room, hearing sounds from the jungle, mountains, the sea, and city environments. In another room, the kids feel vibrations when they play giant musical instruments. They put on special glasses and see sound waves in the Sound-O-Vision room. Can Carlos learn how to get the right sound from his musical instrument in time for the concert?

It's a hot and muggy day, and the heat's gone to Ralphie's head. The Friz asks "What makes the weather?" transforms the bus into a Weathermobile, and in a wild ride through the skies gives Ralphie the opportunity to become the meteorological superhero of his dreams.

Flora Whiff (Bebe Neuwirth), the famous expert on smell whose "nose knows" comes to school to judge the First Annual Smell Search. Ms. Frizzle's class creates a unique smell which is bound to take first prize, but Arnold's cousin, Janet, determined to win by herself, changes their smell to an odor only a skunk could love. The kids discover the secret to what makes things smell... now they have to make sure their creation doesn't make a big stink!

There's something dazzling in Ms. Frizzle's closet: a magical, light-powered pinball machine! To win at this game, the kids have to light up all six colors of the rainbow. Now the race is on, as the class shrinks down and zooms into the pinball machine. Catch an eye-full of fun as they try to crack the secret code of what makes color so....colorful!

When Wanda's favorite singer, Molly Cule (Wynonna Judd), comes to town, she chooses Ms. Frizzle's class to wash her famous car. The kids clean it from top to bottom, but when Molly insists they missed a spot, they shrink down to see the molecules that make up the car. Only then can they discover how to clean it down to the very last bit. But time is running out - they'll need a molecular miracle to get the car clean before Molly's concert begins!

It's "Accidental Science Project" day, and the class has brought in marvelously rotten entries from the backs of their refrigerators. Later, when the Friz shrinks the bus down to "take a closer look" at rotting options in an abandoned lot, the class discovers that there's more to rot than first meets the nose.

In the TV show "OUT OF THIS WORLD," Dorothy Ann, an amateur astronomer, discovers that an asteroid she's been tracking is on a collision path with Walkerville Elementary School! Before you can say, "Get messy"! the kids find themselves in outer space, trying to track the path of the asteroid and send it on another course before it destroys the school.

Dorothy Ann loves her physics book. Ralphie loves baseball. Ms. Frizzle ingeniously combines the two in a page-hopping adventure through Dorothy Ann's book to a "Frictionless Baseball Game." The whole class learns about pushes and pulls in a remarkable day at a thoroughly unique ball game.

When the Magic School Bus's engine stops running, Mr. Junkett, a vehicle maintenance inspector, decides the bus should be junked. The class shrinks, dons fireproof suits and masks, and heads for the engine -- from the inside! There, they discover that the peanut-butter that Junkett accidentally dropped into the engine is blocking the fuel line, stopping air from mixing with gas, and keeping the spark plugs from sparking. While cleaning up the mess, the kids learn how an engine works. Can they get the bus working again before Junkett has it pounded into a pancake?

To celebrate the founding of Walkerville, Ms. Frizzle's class sculpts a stone likeness of its founding father, Captain Walker. But as they add the finishing touches, the statue tumbles down the mountain. Ms. Frizzle turns the bus into a giant boulder and the kids into rock kids. They bump down the mountain in a desperate attempt to save the statue. By the time they reach the celebration at the base of the mountain, they've been pushed, tossed, sanded, polished, and eroded by water as has the statue, now the size of a soccer ball. The kids are sure they've let everyone down until they look back at the mountain for the surprise of their lives!

When the kids see Horace Scope (Dabney Coleman) on the Star Shopping Network, they decide to buy Dorothy Ann a real twinkling star for her birthday. Before buying it, the kids blast off in the Bus to inspect the merchandise. They visit a young star and then a middle-age star and decide that it's the third and last star they want to buy. But when they give Horace their money, KABLOOM, the star explodes! Have they lost DA's star forever?

It's the International Show-and-Tell Competition and Arnold and DA are representing Ms. Frizzle's class. Arnold brings a webbed hoop, left behind by his great-aunt Arizona Joan, the famous archaeologist, but he has no idea what it is! Using clues from the hoop and Joan's journal, the kids make educated guesses about its uses. To test their hypotheses, Ms. Frizzle turns the bus into a "Supposatron," a magical device designed to evaluate guesses. Can the kids solve the puzzle before Arnold and DA take the stage?

What do you do when a 50-foot praying mantis menaces your town? Run like the wind... unless you're in Ms. Frizzle's class and she's taken you on a field trip inside a 1950s sci-fi film. The movie's main character, the power-mad General Araneus (Ed Asner) is determined to destroy the mantis, but Phoebe wants to trap it and save it! Shrinking to the size of real spiders, the kids discover how spiders construct a variety of silky snares, making them world-champion trappers. Can the kids save the mantis and stop Araneus before it's too late?

When Wanda discovers that one of Ms. Frizzle's ancestors was Redbeard the Pirate, she naturally wants to follow the treasure map he left. The map leads the class to a coral reef, where they learn first hand that life there is risky. To survive, they find, many plants and animals form surprising partnerships. But Wanda's not interested in partnerships - she just wants to find that treasure! When Ms. Frizzle turns the class into different sea creatures, Wanda as "Wanda-Anemone," "Wanda-Shrimp," and "Wanda-Remora," begins to understand that partnerships are more valuable then she thought.

In the TV show "TAKING FLIGHT," the remote control of Tim's model airplane is accidentally broken. Wanda and the class find themselves inside the plane learning what it's really like to fly it. In a series of high adventures up in the air, they discover how wings and moving air affect lift and flight, and make it back in time to compete in the Walkerville Model Airplane Rally.

Were dinosaurs the biggest, meanest animals that ever lived? To find out, the kids travel back to the Late Cretaceous Period - 67 million years ago. There, they see dinosaurs eat, hunt, rest, and fight. Some even take care of baby dinosaurs! The kids discover that not all dinosaurs were huge - some were as small as rabbits. And most dinosaurs weren't killers - they preferred plants to dino-burgers. But one meat eater - Tyrannosaurus rex - has a taste for a Magic School Bus sandwich! What happens when Ms. Frizzle enlarges Arnold to T-rex size? Does the Cretaceous creature drop his dinner plans?

Two inches tall, and trapped in a bathroom at Wanda's house, the kids have to get out before Wanda's mother (Rosalind Chao) discovers them. Gathering building materials such as spiky hair curlers, sticky Band-Aids, dental floss, and Q-tips, the kids use what they've learned about structures to construct a series of towers and bridges across the bathroom to an open window! They get across the toilet OK but will they get past the alligator in the bathtub?

In the TV show "UPS AND DOWNS," a monster is sighted in Walkerville Lake! Wanda wants to be first to go under water to find it, but the bus refuses to sink! Meanwhile, Gerri Poveri, a journalist, who needs this monster to boost her sinking ratings, doesn't want Wanda anywhere near the lake. The kids discover there's more than one way to make a bus sink, and in the process discover the real monster of Walkerville Lake.

In the TV show "WET ALL OVER," Arnold and Wanda are due to give a report on the town waterworks. But Ms. Frizzle thinks it's field DRIP time! She turns the bus and class into water drops and the kids evaporate, condense, become rain and rush by river into the ocean. After several trips through the water cycle, they're ready to turn back into regular kids. But the magic key that will get them out of the cycle is locked in the school bathroom! Trying to work their watery way into the bathroom, the kids go through the town waterworks and see how water is purified. Can they get to school through bathroom pipes? Or are they stuck in the water cycle forever?