The first question to consider is whether the term of copyright has elapsed:
The Canadian Copyright Act provides that copyright protection automatically exists in every original literary, dramatic, musical and artistic work when it is created. In most cases, protection lasts for the life of the author plus 50-70 years, after which it is often referred to as being in the public domain. If the creator died in 1971 or earlier, the period is 50 years from the end of the year of their death. If the creator died in 1972 or later, the period is 70 years from the end of the year of their death.
Copyright also subsists in certain “non-traditional” subject matters, such as performances, sound recordings, and broadcast signals, where the clock generally starts from the first performance of the work. Much of the material that you will use in your research and teaching will fall under Canadian copyright protection. You can, however, use the to perform a quick search to see if protection exists on a given work.