Roberto, You're right and she's wrong, and the way to make that clear is to talk about the role of the which in the clause it introduces. It's a relative pronoun, and it stands in for the word group it modifies. If you substitute those classes (what it modifies) into the relative clause, you get nonsense. Those classes Constructiviist teaching is not the primary approach. She could rewrite the sentence so that which is in a subject role, such as In those classes which do not use Constructivist theory as their primary approach. Here, it becomes even clearer, also, that the semicolon is not being used well. In both cases, it follows an introductory prepositional phrase (including a relative clause modifier for the noun phrase object.) This certainly defies traditional advice. I'm not one to advise against following all traditional rules, but I can't think of a good (functional) reason for the semicolon here. If I'm confusing you at all, let me know and I'll try to make the argument less technical. You're initial instincts are absolutely right. Craig