Classroom communication differs from mass media in one decisive respect: it is two-way. The teacher speaks, learners respond, and the teacher adjusts from what the responses reveal. A lecture that never checks understanding is closer to broadcasting than to teaching.
Worked example: a teacher asks a question and immediately answers it herself. Learners learn to wait, not to think. The same teacher, asking the question and waiting silently for ten seconds, gets hands up and real answers. The only change is wait time — the silence that lets thinking happen.