A brief description of Mrs. Franklin is given in her sole appearance, claiming that she has long, gray hair tied in a ponytail and small spectacles. It is likely that her design is meant to reflect Benjamin Franklin, a figure in U.S. History.
As a teacher, she is very good at her job. She is able to teach the students many things in one day that would take Mrs. Jewls a whole month. However, she is also easily fooled, since the prank the students pulled on her worked, making her believe everyone in the class was named Benjamin (though, it was really just Benjamin Nushmutt attempting to reveal his real name, which the other students mistook for a prank). She seems to get along with the students fairly well, as they all miss her when she leaves at the end of the chapter.
She only appears in the chapter "The Substitute", where she takes over Mrs. Jewls' class for a day, but is fooled to believe all the students are named Benjamin. At the end, she reveals that she is actually named Benjamin as well, much to the other students' surprise.
The students question whether or not her first name really is Benjamin, or if she just caught on to their prank.