In Matilda What did the trunchball do to the boy who couldn't spell 'what'?

In "Matilda," Miss Trunchbull punishes a boy named Bruce Bogtrotter for misspelling "what" by making him stand in front of the class and holding a heavy piece of chalk above his head. This humiliating punishment exemplifies her cruel and tyrannical nature as a headmistress. Ultimately, Matilda's cleverness and bravery inspire her classmates to stand up against such tyranny.