I'd suggest doing some research on the expected salary prior to the interview. If you have a general idea of the salary given to similar positions in the same city you're one step ahead. The Canada Salary Calculator can provide information based on job categories in your province or postal code area.
Penelope Trunk's blog discusses how to avoid proposing the salary before your employer. This is a good strategy because you don't want to shoot too high or low. If you are stuck and need to respond, you could answer something along the lines of: "I've been told a position of this stature would generally offer between $ - $"; this way you are restating your advice rather than providing a definite answer. Also saying something like "I believe the salary of your previous employee in this position would be fair" could open up a negotiating conversation.
Thanks for the response Chris! And thank you to the students asking on Jack's facebook!
Samantha Del Duca