Who is the protagonist of The Wednesday Wars?
A protagonist is the main character of a story—the star of the show, you might say. Some novels have more than one protagonist, but it's more common for a novel to have one protagonist and for the rest of the characters to be secondary. This is true of The Wednesday Wars. The story has lots of characters, but only one protagonist.
Holling Hoodhood is the protagonist because he is the one who is at the center of the story. We learn the most about Holling (his family and friends, his struggles and triumphs at school and at home). The story is even told through Holling's first-person perspective. That means the narration is written as if Holling is speaking directly to the reader, using "I" to refer to himself. This becomes clear in the first few sentences of the novel:
Of all the kids in the seventh grade at Camillo Junior High, there was one kid that Mrs. Baker hated with heat whiter than the sun.
And let me tell you, it wasn't for anything I'd done.
It's also clear that Holling is the protagonist because he is the character who changes the most throughout the novel. It's essential for a protagonist to grow and change in a story, and Holling certainly does. He learns a lot about himself, the people around him, and the world he lives in.
You can read more about The Wednesday Wars here.