Time and again, I have faced a situation in which I want to express something about what the teacher/lecturer is teaching; however, I have to say it indirectly, as I did now.
For instance, consider this sentence, please:
Using electronic devices in the classroom distracts students from … .
Should I say “the subject”,”the material”, “the lesson”?
Use either “the lesson”, or “the lecture”.
All three of those are correct, as all three are commonly understood to refer to what a teacher is teaching. But if you want to make sure that it is clear that it is something being taught by a teacher, then use either “the lesson” or “the lecture”, and not “the subject” or “the material” because both of those could refer to a multitude of other things not related to teachers teaching.