Just a tip with using the Smart Share function in TD: make sure the document you are trying to share is owned in the staff domain. For example, documents owned by a teacher's personal email account, such as a gmail account, can't be smart shared* even if they have been shared with the teacher's @syd CloudShare account as an editor.
Clearly, the simple solution is to make a copy of the document in Drive (or upload the file to Drive in the case of PDFs, Word docs, videos etc) so this new document is owned by the teacher's @syd CloudShare account. There's more information about making a copy or uploading files.
* The reason for this is security. it's a way of ensuring that only content that is owned within and therefore managed by our staff CloudShare domain (syd.catholic.edu.au) can be distributed to students.