Mr. Cooper is Super is the first book in the My Weirdest School series.
AJ and the gang at Ella Mentry Elementary School are in for a super surprise when a new teacher, Mr. Cooper, takes over their third grade class.
The book begins with AJ saying that he hates it when a spaceship lands in the middle of the playground. He isn't kidding when he says that a UFO actually landed in the middle of his school's playground.
One day, AJ and his friends are playing on the playground, when a spaceship lands in the middle of the playground, making AJ recall the time when Mr. Granite became his third grade teacher, and how he found out that Mr. Granite was an alien from another planet. Once the spaceship lands, an alien who looks like Mr. Granite comes out of it. Then a few more aliens who look like Mr. Granite come out of the spaceship. AJ is surprised at this and wonders which is the real Mr. Granite. Mr. Granite then tells AJ that all the aliens are the real Mr. Granite and that they are from Mr. Granite's home planet, Etinarg. AJ is amazed that Etinarg is filled with men named Mr. Granite and thinks that might get kind of confusing.
All the Mr. Granites are very happy to see each other, and the aliens ask Mr. Granite if his students harmed him in any way. But Mr. Granite tells them that they're very well behaved. AJ asks the aliens if they're going to turn him and his friends into zombies, robots, or killer slaves, but the aliens say no and that they are going to return Mr. Granite to Etinarg. This makes AJ and his friends panic.
AJ knows that he and his classmates all love Mr. Granite and don't want him to leave. Mr. Klutz tells the aliens that Mr. Granite has been teaching at Ella Mentry Elementary School for a long time, and he asks them why they're showing up all of a sudden. The aliens tell Mr. Klutz that Etinarg is many light-years away from Earth and it took them a long time to get to Earth and that they also got stuck in space traffic. AJ suspects that the aliens are lying about that, as he believes that there's no such thing as traffic in outer space.
AJ then wonders if the aliens will peel their faces off, like the ones he sees in sci-fi movies. He asks the Mr. Granite aliens if they are going to peel their faces off, and they do so, which frightens the kids, including AJ, even though he wants to see what they look like underneath their skin. Once the aliens peel their faces off, AJ realizes that they all have the same faces as before. AJ and his friends are amazed that the aliens' faces look like the ones they peeled off.
Everyone is very sad that Mr. Granite is leaving. They beg Mr. Granite not to leave, but Mr. Granite tells them that he has to return to his home planet. Emily asks Mr. Klutz to do something about it to allow Mr. Granite to stay. But there's nothing Mr. Klutz can do. He tells Mr. Granite that everyone will miss him at Ella Mentry Elementary School. Mr. Klutz tells the kids that they borrowed Mr. Granite from Etinarg and now they have to return him. Mr. Granite tells the kids that he really enjoyed teaching at Ella Mentry Elementary School and he feels sad to leave and that he will miss his students more than anything else, and when he returns to Etinarg, he will name his friends after his students.
As everyone bids Mr. Granite farewell, he reminds the kids to remember what he told him during their year with him. AJ remembers what Mr. Granite told him, which included "Sit down, Be quiet, Stop bothering Andrea, No, you can't go to the boys' room now, Where's your homework, Go to the principal's office" and most of what Mr. Granite told AJ was "Stop talking". As the spaceship is about to leave, Mr. Granite reminds his students to turn to page twenty-three in their math books.
As the spaceship leaves, everyone is very sad to see Mr. Granite go. Andrea asks what they should do now that they don't have a teacher. Suddenly, AJ realizes that if they didn't have a teacher, they wouldn't learn anything, and there'd be no point in going to school, meaning that the school would have to shut down. He is very excited about this idea, but he finds out that the other kids don't really feel the same way as him. Mr. Klutz says that they'll find another teacher tomorrow.
The next morning, AJ anticipates on what his new teacher will look like. When he walks into the classroom, he sees that the teacher hasn't arrived yet. Alexia says that she wonders who their new teacher will be. Ryan asks AJ where someone would go to get a new teacher, and AJ says that teachers could probably be rented. Andrea says that they'll probably have a substitute teacher for a few days, because Mr. Klutz will need some time to hire a new teacher. AJ asks if teachers get paid when they get hired, and Andrea says that it's true.
Emily thinks that Mrs. Daisy, their old second grade teacher, might be their substitute teacher until Mr. Klutz can hire a new one.