Sometimes what you teach is part of a puzzle of continual concepts that build the picture. When you have a large amount of material to cover, consider "jigsawing" the job out to the students. This means asking a student or group of students to read, study, and report on a part of the lesson they master. You might give each student or a pair of students a verse in which they are required to look up the meaning of that in the commentary or other sources you provide. Invite them to become experts in that one portion and they will have to pay attention to the other parts as well. You might assign this ahead of time and use the time in class to report and put the puzzle together.