When a new substitute shows up, K.O. and Dendy decide they need to get their old teacher back.
Tropes:
- Abnormal Ammo: As the Bad Apple, Miss Quantum shoots red Xs out of her Arm Cannons. Although they sting, they're ultimately just harmless red ink. In the end, a reformed Miss Quantum shoots "good job" stickers on K.O. and Dendy.
- Comically Missing the Point: After Dendy explains that Ernesto is turning the students' brains into pudding, K.O. thinks that pudding brains sound delicious.
- Deliberately Monochrome: The color is desaturated when Ernesto is brainwashing the students.
- Doomed Supermarket Display: Miss Quantum knocks over a display of exploding chili cans to escape K.O. and Dendy.
- Evil Teacher: Ernesto becomes a teacher at Lakewood Plaza Public School to turn young heroes into mindless zombies.
- Exactly What I Aimed At: Miss Quantum fires at K.O. and Dendy. They realize that she missed them, but she was actually aiming at their hand glider, causing them to fall.
- Face–Heel Turn: After quitting teaching, Miss Quantum decides to pursue her true passion... villainy! So she becomes the Bad Apple and swears revenge on Booksmore.
- Fastball Special: Miss Quantum throws K.O. at Ernesto, and K.O. lands a punch that knocks Ernesto out the window.
- Immune to Mind Control: Dendy is immune to Ernesto's mind control because she's smart enough to realize he's just asking the class to repeat stuff they already knew. As for K.O., he was Asleep in Class and wasn't listening.
- Impact Silhouette:
- Dendy and K.O. follow Miss Quantum, now the Bad Apple, into a cloud, where she has left an apple-shaped hole.
- After K.O. dispatches Ernesto with a Dynamic Entry, his silhouette is left in the window.
- Lesser of Two Evils: Dendy and K.O. dislike Miss Quantum, but immediately want her back when Ernesto takes her place—at least she isn't trying to brainwash anyone.
- Moral Luck: When Miss Quantum is forced to use Booksmore text books, she decides she can't do any good as a teacher, and so decides to be a villain again. As the Bad Apple, she blows up the Booksmore train as revenge for ruining her lesson plan. Turns out Booksmore was actually a front for yet another Boxmore plot, and the textbooks were part of their plan to brainwash the children. Dendy points this out as proof Miss Quantum can be heroic, even though it was a total coincidence.
- Moving the Goalposts: When Dendy completed her math worksheet, Miss Quantum gives her a stack of new ones. It turns out this was not done to be mean, but to keep Dendy challenged, not that the end result is much different.
- Nap-Inducing Speak: K.O. avoids being brainwashed only because he's so bored with Ernesto's monotonous lessons that he falls asleep.
- Noblewoman's Laugh: Miss Quantum does one when revealing herself as the Bad Apple.
- Paper-Thin Disguise: A literal example as Box-More (with that formatting) applies post-it notes to the front covers of all of their textbooks covering over the "x-" in favor of "oks", forming the front brand Booksmore.
- Pet the Dog: After K.O. and Dendy get Miss Quantum to take her job back, she actually congratulates them for once and gives them a sticker.
- Phlebotinum-Induced Stupidity: Ernesto's hypnotic lectures put his students in a trance while gradually draining their intelligence.
- Reality Is Unrealistic: Discussed when K.O. and Dendy enter a cloud.K.O.: Whoa! Clouds are... boring inside.
Dendy: Indeed. Cartoons are so misleading. - Shout-Out: The Booksmore Train song is a parody of "Casey Jr." from Dumbo.
- Something We Forgot: In fighting Miss Quantum and convincing her to return to teaching, K.O. and Dendy forget to stop her from blowing up the Booksmore train.
- Surprise Santa Encounter: Principal Claus, who, it's pointed out, usually only appears once a year.
- Worst. Whatever. Ever!: Dendy and K.O. try to convince Miss Quantum to come back because Ernesto is "the worst teacher ever!"
