The boy who spells "work" wrong is Bruce Bogtrotter, a large, sweet-toothed boy who is forced to eat a gigantic chocolate cake as punishment for stealing a slice.
Miss Trunchbull is a cruel and tyrannical headmistress who terrorizes the children at Crunchem Hall school. She is known for her violent punishments, including throwing children across the room, forcing them to stand on their heads, and putting them in a "chokey" (a small, dark room).
The scene you're describing is a classic moment from the book and the film adaptation. It's a powerful example of Miss Trunchbull's cruelty and the children's vulnerability.