Is params[:student_id] present here? If so, this line isn't needed as this is what `current_student` does:

https://github.com/bellotastudios/gradecraft-development/blob/master/lib/current_scopes.rb#L12-L17

If not, I think the line you have is fine but I believe it needs to be self.current_student = ... as the above will just create a local variable rather than calling the `current_student=` method in lib/current_scopes.rb.