I'm doing a E/R model for a project. I finished the ER model and, for me, all is okay. Maybe not perfect, but it's okay. When I gave the ER model to my teacher, he told me this:

"the m:n relations MUST HAVE some properties"

He said if the m:n relationship doesn't have the properties it will be wrong. In my opinion m:n doesn't need forcer attributes to the relationship, but if you have someone that can fit in it, just put there.

What do you think? Who is wrong in this, me, or my teacher?

NOTE:

Reading again, it seems what he said was not due to my ER diagram, but was a general statement. The diagram I gave him doesn't have relations yet, so there where just entities and atributes.