When a copyrighted song record for distribution or other use, that is an exercise of the reproduction right in the song. CMRRA is in the business of the granting such permission on behalf of the music publishers
This document (updated 2016) provides advice for educators on copyright issues in Canada, relating to print materials, video, music, as well as the internet. This is an excellent resource for teachers.
The University of Alberta created the Opening Up Copyright (OUC) instructional videos to make copyright law more easy, engaging, and accessible to everyone. Check out their many videos, including "Copyright In A K-12 Context."