"Ups and Downs" is the thirteenth and final episode of season two and the twenty-sixth episode overall of the animated children's series The Magic School Bus. It originally aired on December 31st, 1995.
During breakfast, Wanda watches the news of talk show reporter Gerri Poveri reporting that there is a sea monster in Walker Lake (apparently based on the Loch Ness Monster, as it is also plesiosaur-like). Wanda's mother, however, scoffs at this, and tells Wanda that Gerri Poveri is only making this up.
Wanda rides to Walker Lake, only to find that the class beat her to it already. Phoebe uses a banana as a bait, only for it to float. Carlos jokingly states that he likes banana splits better. Tim decides to use his monster camera (wrapped in a plastic block) to send it to get a better view of the monster, only to find that it floats too. Wanda arrives just in time to dress in her swimsuit (dressed under her clothing) prepared to catch the Loch Ness Monster. Ms. Frizzle then arrives, despite the fact that it is the weekend, and Wanda explains to her about the picture of the Loch Ness Monster the talk show reporter on television showed on television. But Dorothy Ann reminds her that pictures can be fake. Gerri Poveri arrives via helicopter and warns the others to stay out of the water. The others, however, don't heed the talk show reporter, for they are very eager (especially Wanda) to find it, and Wanda notes that Gerri doesn't own the lake. So The Magic School Bus arrives and Liz transforms it into a submarine.
Everyone enters The Magic Busmarine. However, The Magic Busmarine's automatic sinker lever is rusted (as Liz forgot to swab the deck and dry the sinker linker the last time The Magic School Bus went underwater). They will have to find some other way to get it to sink. Using Phoebe's juxtaposition of a floating banana and a sinking rock, the class succeed by adding weight and "crumpling" the bus. Liz steers the submarine bus as the class navigates through the underwater lake, oblivious that Poveri is also there in her underwater boat. She uses it to untie the weights supplemented to The Magic Busmarine, causing The Magic Busmarine to resurface.
Once on top of the surface of the water, Ms. Frizzle tells the class that the water pushing The Magic Busmarine is what causes it to float. So Tim decides to supplement rocks inside the plastic box to sink his camera underwater. Phoebe tries to feed the Loch Ness Monster a peanut butter sandwich, only for one half of the bread to float on top of the water. Phoebe then crumbles the other slice of bread to a small ball and tosses it into the water, only to discover that it sinks, as opposed to the bread slice. Ms. Frizzle explains that it is the size of the breads that differ: the big, flat slice floats while the small, balled-up one sinks.
So the class enter The Magic Busmarine and Liz activates the crumple buttons, causing The Magic Busmarine to crumple and sink. The class learns that the more The Magic Busmarine crumples, the less water it shoves out of the way, and the less the water pushes back on it. As The Magic Busmarine finally hits the bottom of the lake, Wanda exits it, which begins to float up again. Wanda gets her leg caught by an underwater seaweed, and the bus can't get any smaller because of the crumple buttons being jammed. Carlos exits the bus and pulls the plugs off the bus to release some of the water inside, causing it to sink again. Wanda, meanwhile, finally comes across what appears to be a Loch Ness Monster.
As Wanda struggles to extricate herself from the seaweed, she inadvertently punches the monster and its nose breaks off. Wanda then realizes that it was only fake, and then pulls apart the seaweed around her leg. She then says that her mother was right: “There is no monster; it’s all just pretend!”
Wanda rebukes the talk show reporter for what she did, which Poveri calls "creative journalism". Wanda swims to The Magic Busmarine and informs the rest of the class about her findings. Arnold suggests that the class should use air to push the water out to make The Magic Busmarine float again, since air is lighter than water. So the class pumps air into The Magic Busmarine to pump the water out, and The Magic Busmarine begins to rise on top of the surface again.
Unfortunately for them, Poveri uses one of her gadgets of her underwater boat to pull one of the plugs of The Magic Busmarine to cause it to sink again, and Poveri returns on surface to record the news.
Back underwater, the class view the fake monster about to float on top of the surface of the water, giving Phoebe an idea to un-crumple The Magic Busmarine to expand in size. This plan works, and Wanda and Tim use Tim's camera to get a footage of the fake monster. Wanda released the the fake monster from the rope which causes it float and burst out of the lake right underneath Poveri's helicopter, knocking her into the water and Wanda unplugs the fake monster, causing it to deflate as Tim gets the footage of it.
At Poveri's talk show, the class are seen with the talk show reporter, who apologizes to the viewers for her deceitfulness as the footage of the truth is being shown on camera. Ms. Frizzle concludes that "the truth always floats to the surface" (as Gerri herself said).
- Arnold doesn't say "I knew I should've stayed home today" in this episode.
- This is one of the episodes where Arnold wasn't nervous about the field trip.
- Wanda's last name is revealed to be Li.
- Ralphie is seen without his cap during one of the underwater scenes.
- Instead of the producer, Gerri Poveri appears in the Phone Segment answering the phone.
- The first time The Magic School Bus sinks underwater with the weights attached to it, it started moving through the water like an actual submarine. The second time it sinks when crumpled up to a small size, it keeps on sinking till it hits the bottom. Perhaps the propeller couldn't turn when The Magic School Bus was crumpled because it was too crumpled up for the propeller to turn.
- To crumple the bus, Liz activated four crumple control buttons to crumple up The Magic School Bus to cause it to sink. To uncrumple it, the kids pulled hard on each side of The Magic School Bus, while Ms. Frizzle and Liz pushed hard on the inside of it. Perhaps they couldn't use the crumple control buttons to uncrumple The Magic School Bus like they used them to crumple it because they were still jammed (as Ms. Frizzle said when they were rising back up to the surface when Wanda left them).
- Carlos' voice sounded like a teenager in the first 2 lines he spoke in this episode. The reason for this is because Daniel DeSanto was going through puberty at the time.