When Wanda's favourite 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!

When the principal, Mr. Ruhle (Paul Winfield), has to go away for a few days, he leaves his beloved chicken, Giblets, in Dorothy Ann's care. Unfortunately, the minute Mr. Ruhle is out the door, Giblets flies away. How will DA ever find another prized Rhode Island Red to replace Giblets? Where do you get chickens anyway? And which comes first, the chicken or the egg? The next thing DA knows, Ms. Frizzle and the class are on a field trip to see how eggs are made — from the inside out! But will this egg have everything it needs to become ""Giblets the Second""?

The class is enjoying a normal summer day at the beach until Ms. Frizzle discovers a letter from ""Uncle Shelby,"" who wants the class to look after his beachfront property. The kids soon discover that this ""luxurious"" accommodation is only a tiny spot on the shoreline. Why would anyone want to live in a spot where they're battered by waves at high tide and baked by the sun at low tide? To find out, Ms. Frizzle turns the kids into... mussels!?

""We got assigned air, and it's not fair!"" The only contribution the kids in Ms. Frizzle's class have made to the Walkerville Space Capsule is an empty jar. ""It's not empty,"" argues Keesha. ""It's filled with air!"" ""But air doesn't do anything!"" wails Ralphie. They discover that's not so when the bus shrinks and gets stuck inside the jar — and the class finds that their only hope for escape is... air!

The debate is intense: Should Walkerville get rid of the swamp by the river and replace it with a fantastic new shopping mall or build the mall somewhere else? Carlos, representing his class, is given the thankless task of persuading the town council to keep the smelly old swamp. If he loses the debate, he'll lose to Arnold's pesky cousin Janet! The kids learn that the swamp is an important habitat and natural water filter, but the council's not convinced until... FLOOD!!

It's the night of the rock lovers' annual Granite Awards, and Arnold is about to become the first kid ever to win the coveted Rocky Award. He's so excited, all he's been able to eat for weeks are ""Seaweedies"" — and lots of them! When he arrives for the big event, he's totally nervous and totally...orange! Once the class determines that the orange isn't on Arnold's skin, they shrink down to explore what's underneath. They discover that his whole body is made of living cells — and they're all orange! But where is the orange coming from... and how can they make it go away?

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?

Guess who's selected to give an exhibition of a slam-dunk during half time of the big basketball game? Phoebe! The problem is Phoebe can't jump high enough. ""If only gravity didn't pull on me!"" she moans. Never one to be tied down, Ms. Frizzle sends the class into space and turns the Bus into a planet — with adjustable gravity! Basketball's a snap with low gravity and a riot with no gravity at all, but when there's way too much gravity, things get really heavy! With Paul Winfield as school principal, Mr. Ruhle.

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 odour 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!

It's Valentine's Day and the class is selling lightbulbs. When they stop at Ms. Frizzle's house to sell her one, they find that her battery-operated doorbell doesn't work. While looking for Ms. Frizzle to tell her the doorbell's broken, Wanda overhears her teacher talking on the telephone. ""Ms. Frizzle has a boyfriend,"" says Wanda, ""and he's on his way over to see her! We've got to fix the doorbell or she'll never know he's here!"" But first they have to figure out how the doorbell works...

Ms. Frizzle's class arrives early to open the school for Mr. Ruhle (Paul Winfield). But there's so much to do! ""There must be a way to do all of these chores without actually doing them,"" says Carlos. The school handyman, Mr. McClean (Malcolm McDowell) is in total agreement. Enter Mr. Ruhle's new computer and Mikey, Carlos' whiz kid brother, who programs it to do all the chores! But when Ms. Frizzle shrinks Mikey and the class and sends them inside the computer for a guided tour, everything goes haywire. The only person who can fix the problem is Mikey - and he's just landed somewhere between the CPU and the hard drive!

Ms. Frizzle's class is visiting the zoo, which is, according to Tim, the only place in the city where wild animals can survive. To test this idea — ZAP! — Ms. Frizzle turns the class into possums, foxes, and falcons! The Bus, with Liz inside, becomes a bear and wanders off, looking for food. Will the kid-animals be able to find the Bus-bear before the zookeeper finds it? And is Tim right? Can animals (like themselves) survive in the city?

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.