The first teacher?

You are correct...I thought the same....to be honest I think as the most possible explanation that the rest of her scenes were deleted (for an unknown to us reason).

I had this exact same question. I thought she was one of the sisters at first and I was surprised that she completely disappears from the story. It must have to do with the way it was edited and they cut the rest of her scenes. She was probably a victim anyway.

Avati and his family moved from Bologna to the countryside during the bombing of Italy in WWII and so he grew up in rural Italy in a small, country village. Much of the film is based on the rural folk tales (the female priest for one), superstitions and the colourful inhabitants who he observed as a child. As a result, we get stereotypical characters such as the town drunk (Coppola), the town loon (Lidio) and, sexist as it may be, the notion of the ageing, single woman who has sex with everyone in the area. So I guess she is just another part of Avati's vision in depicting the rural Italy in which he grew up.