In Nothing But the Truth by Avi, Mr. Lunser and Ms. Narwin have very different personalities. Mr. Lunser is a joker. When Philip is in his homeroom, Mr. Lunser makes sarcastic remarks about everything that is said on the morning announcements. He is actually the one who gives Philip the idea to hum along with the national anthem when Philip continues to work on an assignment during the song.
Phillip Malloy: Just one last paragraph?
Mr. Lunser: Away, Philip! Or I'll make you sing along solo! (Avi 6)
On the other hand, Philip has already decided he does not like Ms. Narwin when he is transferred to her homeroom. She is a no-nonsense kind of teacher. She is there to teach, not to make jokes, and she has high expectations for her students. She is also a rule follower, and when Dr. Doane says,
"Please all rise and stand at respectful, silent attention for the playing of our national anthem," (Avi 6)
Ms. Narwin expects her students to do exactly that.