Eli is the last in a long line of his family to attend the school, so he's always being compared to his brothers. When told he has to participate in the annual Science Fair (so his dad can get out of judging it), he decides to re-do one of his older brother's past experiments. Shohei, a perennial slacker, joins in with him, figuring it'll be an easy out.
When Eli's results don't match his brother's (and the science teacher dismisses Eli's results in favor of said older brother), Eli finds himself battling Mr. Eden. He just can't back down, since he knows he's in the right.
That's kind of the main plot line, but there's a lot more than that going on. Shohei, a Japanese boy adopted by Irish parents who are on a mission to make sure he's properly introduced to his culture -- whether that means re-decorating his room and putting in a Zen garden or packing him sushi for lunch -- is in a battle to find his own identity.
Meanwhile, Eli's got a crush on Honoria and Honoria has a crush on Shohei, which she confides to Eli. That puts him in a tough spot, as you can imagine (and a classic one at that -- it even takes a brief Cyrano de Bergerac tack).
Everything works out in the end, one way or another. Told from all three viewpoints, the reader gets to see all sides of the story and sympathize with each one. You have to cheer for Eli as he stands up for himself, and you can't help but laugh at Honoria and her preoccupation with bugs (which ultimately helps Eli out of his situation, in an un-orthodox bid to get Mr. Eden to work with him).
I recommend this book for ages 10 and up, boys or girls. It's a fun read. I just wish I could have gone to the Peshtigo school...