What is the main purpose of introducing Shanzai?

I think it is to show the contrast between miramin and Lila to show how lila has an education and is breaking through barriers.

Shanzai is the children's teacher. She announces that she is the "daughter of a poor peasant." She did not cover up and forbade other girls to do so. She said that, "women and men were equal in every way". The teacher represents a radically different thought on women in Islamic society. Her opinion is uncommon. Indeed it is uncommon and dangerous for a woman to have an opinion at all. She symbolizes a type of progress that is elusive to women but also has an effect on the girls. She is an example of possibilities.