Phoebe and Max want to help Billy and Nora with their science fair at Billy and Nora's school. While the science fair, a huge tomato explodes which Max causes. Barb makes a book club which Hank ruins.
Phoebe finds Billy and Nora working on their science fair projects. Phoebe geeks out about how she loves science fair and how fun it is. She asks about their projects. Nora is making a potato clock, but gets hungry and turns them into french-fries using her heat vision. Billy is making mop socks for cleaning the floor. Phoebe is not impressed. She asks them not to mention science fair to Max because it brings back bad memories. Of course now they have to do it. Both Billy and Nora shout "SCIENCE FAIR" for Max to hear. Max freaks out and comes down crashing through the wall. Literally.
In a flashback, Max explains how his dreams were crashed 5 years ago back in Metroburg when he made the best project by coming up with Growmatic machine, a device that made everything bigger. Unfortunately, the device melted things after making them bigger. And therefore, he failed the project, losing to Phoebe. Phoebe then literally rubbed the medal on Max's face showing off about her first. The present day Phoebe starts bragging about the medal again. Max says he will have his day. On a completely different note, he asks Nora about her project and asks to help. Billy says they're not supposed to get help but Max makes it sound less bad. Billy then says that if Billy is getting help, he must get help too. Phoebe quickly volunteers to help.
Phoebe thinks Billy's idea of making a mop is too dumb. She forces him to change his project to a volcano. Like Phoebe, Max replaces Nora's potato clock idea by doing Growmatic 2.0 of his failed project to make things bigger. Nora wants to put one of Nora's Bows on the machine, but Max kicks her away and makes her get him a sandwich while he works on the machine. Phoebe comes in and asks Max why he changed Nora's idea. Max admits that he has issues. He says that he wouldn't do a lame project like a volcano. Phoebe feels embarrassed and runs back to Billy to switch from her volcano idea. She then sends away Billy to get supplies as she works on the project.
Max and Phoebe take over Nora and Billy's projects completely, making it clear that it's becoming a rematch of their science fair. The competition tension intensifies between the Thunder Twins. They start fighting and when Nora and Billy complain about it, Phoebe and Max tell them to stay out of it. After losing their science projects to their older siblings, Billy and Nora are stuck in the kitchen making sandwiches and getting snacks while Phoebe and Max do their projects. Nora whispers an idea to Billy on how to get back at Max and Phoebe.
During the Science Fair, Phoebe and Max go with Billy and Nora to school to present their projects. Phoebe refuses to let Billy touch his own project. Max comes to make fun of Phoebe's "fan" project which is actually a power-generating turbine which can generate enough energy power the entire school for a whole year. After the Phoebe-Max fight, Nora and Billy discuss about their "Operation Sibling Sabotage" plan to stick it up to their siblings.
Billy introduces his project as his fan "Mr. Windy" but Phoebe takes over calling it the "high-efficienty bi-directional power-generating wind turbine." Billy says that he doesn't know what the big fan does. So, Phoebe takes over and explains how it works. She asks Billy to demonstrate but Billy claims he doesn't know. So, she takes over. The fan rotates in the wrong way, sucking a lot of things from the room, including the teachers' shirts. One of the teachers is wearing a t-shirt written "Hottie with a body." Billy's teacher understands that Phoebe is a big state trying to relive her glory days. He disqualifies Phoebe's project but Phoebe brags about how she is a champion. She shows him her medal but he takes the medal away from Phoebe on behalf of scientists everywhere.
Max rejoices during Phoebe's embarrassing moment. He then takes over the floor to introduce Nora's project. Nora tries to talk but Max shuts her out. Max then shows off his Growmatic 2.0 machine and demonstrates how it makes things bigger by expanding a tomato. The teacher is very happy with the project since it could help end world hunger. He announces Nora as the winner of this year's science fair project but Max takes away the medal from the teacher. Max's Growmatic 2.0 continues running until the tomato explodes on everyone in the room. The teacher takes away Max's medal. Max says his machine did its purpose and nothing melted... but then the machine itself melts.
The Thunder Twins confront Nora and Billy for sabotaging their projects. Nora says that's what they get for taking over their siblings projects. Phoebe and Max go home disappointed, not willing to talk about the science fair ever again.
Barb joins a book-club in order to get to know her Hiddenville neighbors. She drags Hank into it although Hank doesn't want to join a book club. In order to convince Hank, she promises him that she will make a meatturduckbalizza, a food Hank really wants. Hank agrees. Hank refuses to read the book while Barb reads and writes notes on the books.
Hank finds Barb's notes and steals them to use them for book-club discussions. He impresses everyone, however, Barb knows that he stole her notes because he says exactly what she wrote. Barb gets mad at him for cheating. So, the following night, she writes bullshit notes and lets Hank steal them. Hank embarrasses himself in front of the whole meeting by saying things that are completely ridiculous and not part of the book. When the other members call him out on this, he accidentally reveals that he copied Barb's notes, after which all the members kick him out. Later when the family eats dinner together, he made the meatturduckbalizza himself, which nobody wants.
- Kira Kosarin as Phoebe Thunderman
- Jack Griffo as Max Thunderman
- Diego Velazquez as Billy Thunderman
- Addison Reicke as Nora Thunderman
- Rosa Blasi as Barb Thunderman
- Chris Tallman as Hank Thunderman
- Dana Snyder as Dr. Colosso (voice)
- Reagan Fernandez as Young Phoebe
- Matthew Villar as Young Max
- Joey D'Auria as Science Fair Judge #1
- Waymond Lee as Science Fair Judge #2
- Renee Percy as Lisa
- Keith Lal as Book Club Member
- Phoebe and Max being both very smart and competitive was first introduced in Report Card and has become a continued theme for the Thunder Twins.
- Both Max and Phoebe use Billy and Nora for their personal gains frequently.
- Billy and Nora would take similar action on their older siblings in Are You Afraid of the Park?
- This is the second time we see a glimpse of Phoebe and Max's school in Metroburg. The first time was during picture day in Phoebe vs. Max.
- Billy's habit of licking foods or snacks is seen again later in "I'm Gonna Forget You, Sucka" when he keeps walking around licking fruits and returning them and even President Kickbutt notices it.
- This is the lone episode where Billy and Nora were not seen to talk to Hank and Barb.
- First new episode to air in 2014.
- This episode got 2.2 million viewers.
The image gallery for Weird Science Fair may be viewed here.