Who storms into the art room to try to break up the fun in speak?

In "Speak" by Laurie Halse Anderson, it is the character of Mr. Neck who storms into the art room to try to break up the fun. He represents authority and the tension between the students' creative expression and the rigid expectations placed upon them. His intrusion highlights the conflicts the protagonist, Melinda, faces in her struggle for self-expression and the challenges of navigating high school life.