"Wet All Over" is the sixth episode of season two and the nineteenth episode overall of the animated children's series The Magic School Bus. It originally aired on October 14th, 1995.
Arnold and Wanda are getting water for their waterworks project in the girls' bathroom. Arnold voices his concern of getting caught, to which Wanda teases, "Who's going to catch you in the girls' bathroom? Tiffany?" He denies knowing such a girl. As she takes the bucket of water back to the classroom, he stays behind, only to get caught by Tiffany, who runs away in shock.
Arnold returns to the classroom to set up the project when Ms. Frizzle explodes from her closet, surfing on a rush of water. A field trip to the water park, Water Land, is suggested, but instead, the class ends up going on one in the water cycle. When Wanda realizes that she doesn't have the keys she borrowed from Ms. Frizzle, Ms. Frizzle uses her spare key instead and the bus, along with the rest of the students, transform into the matter of water as they fall into the water cycle. When the sun shines brighter, the water gets warmer, and the students, Ms. Frizzle, and the bus float in the air. Ms. Frizzle explains to the class that water evaporates once it is exposed to such high heat.
Meanwhile, Liz realizes that the sink is overflowing and desperately attempts to stop it, but to no avail. As Liz continues to struggle to keep the bathroom from flooding, the rest of the class continue to float in the air and notice that they are vaporizing, and Ms. Frizzle explains that it is what water does, as it is condensing. They then turn into clouds and learn that the wind can takes cloud wherever it blows, taking them anywhere. They then end up getting blown by a gust of wind.
As the class float, they coalesce into one big cloud put together and transform back to water again. But this time, in raindrop form. They end up dropping into a forest and take a ride in the river, where they go down the waterfall and end up in the ocean. They end up evaporating again when the sun shines once again and condense into water droplets. They, once again, turn into clouds and revert to raindrops. When asked by Arnold that water never stops moving, Ms. Frizzle explains that all of this is called the water cycle. The class then realize it is 3:00, which means they have to get back in class since the class have after-school plans, only for them to realize that it is only 3:00 in London, England in the United Kingdom in Europe, where they end up in.
Unfortunately for the class, there's no way for them to change back, as Arnold left the actual keys to turn them back to human form in the girls' bathroom. Suddenly, Carlos spotted a taxi cab heading right for them. The students begin to panic, but Ms. Frizzle reminds them of the water cycle. The class evaporates once the sun shines just avoiding being run over by the cab and they turn into clouds. When the class learn that stop being water is their only way out of the water cycle, Wanda gets the idea to blow the clouds wherever the class wants to go. As the class manages to get back to Walkerville and back in the school via the waterworks and pipe system, Liz, who stayed behind to try and turn the sink Arnold left on off, uses her tail to stop the water, only to get stuck. Wanda arrives as a raindrop just in time and slams into the window, the impact causes her to drop into a puddle.
Wanda meets the rest of the class to inform them of the flooded bathroom and Liz being stuck in the water faucet. Arnold decides to the water works to get inside the bathroom and the class evaporates once again. They transform into cloud and blow to the water works. There, they transform into raindrops and take a ride in the water reservoir, which Dorothy Ann informs that is where the water everyone drinks is collected, much to Ralphie and Carlos' disgust. The class swim to the mixing base and notice white blobs called alum, in which the dirt sticks to and keeps the water clean. The class swim through the filter and Arnold informs to them that they are in the gravel to get rid of any particles so they, along with the rest of the water, stay clean. They swim through the pipes and come across one with Liz's tail stuck to it. Liz freed when Wanda bites her tail, and Liz gets the key for them. Tiffany returns to the bathroom, only to be washed away by the wall of water building in there.
The class becomes regular size again, and Arnold rushes to help Tiffany. He asks if she's okay, which she is, and she asks what happened. He replies, "I guess you could say our field trip made a real splash. Ms. Frizzle also adds that "To appreciate the water cycle, you've got to have a good sense of humid", which the rest of the class laugh to.
- Tiffany's design is possibly based off of the "seventh grader" in At the Waterworks, which this episodes is adapted from.
- Arnold says, "I knew I should have stayed home today" twice, as he did in "Gets Eaten".
- In 1996, the episode was edited together and released on a home video release "Kids for Character" as a Responsibility segment. Arnold and Wanda also provide the voice-overs during it.
- It is implied that when Tiffany finds Arnold and Wanda in the girls' restroom, she may have needed to use the restroom.
- When Ms. Frizzle surfs on out of the closet in the classroom, she is barefoot, but when she unzips her red wetsuit to reveal a water cycle-themed dress, she is wearing red heels with gray storm clouds on the front.
- Ms. Frizzle puts the spare key into the ignition and starts the bus in one scene. In the next scene, it is no longer in there.