Thanks for your suggestion, Hartmut! The only problem with this that I can see is that I cannot choose to have all users with the role of teacher added to the cohort (correct me if I am wrong). I would need to go into every course and identify the teacher, write that down, then to back to the cohort page and add each teacher individually. This woudl be a LOT of tedious work and as courses and teachers change, the list would quickly get out of date.
Because all teachers are identified with the role of teacher, it seems to be I shoudl be able to choose a role and email everyone one with that role at once. The individuals may change, but I would always be emailing people with that role, so no maintenance required beyond nomal course maintenance.
Is there any way to do it that way that you know of?
Perhaps I am not understanding your original answer, correct me if I am wrong. Thanks again for your help!