You could have a combination of columns as the primary key, in the Module Entity.
Like combination of StudentId and ModuleID, which would be unique.
What's the relation between Student, Module and Assessment?
Like 1 Student will have a particular Module only once, with only one assessment.
If so, then you can merge Module and assessment together.
If this problem was related to the same old you, you could have continued in the same thread, instead of creating a new one