Frindle: Nick's Teacher

What do you think of the character of Mrs. Granger. Isn't she SO mean to make kids write I am writing this punishment with a pen 100 times? She must really want kids to call frindles by their real names - pens!

What do you think about this? Is she right to insist that kids use the correct word, not a made-up one? Why is she making such a big fuss about this? Is she just horrible? Or is she just doing her job?