drum in
To teach something (to someone) through repetition. A noun or pronoun can be used between "drum" and "in." The teacher tried drumming in the material before the state exams, but he was still concerned that the students weren't getting it. You never listen to what I'm telling you! Do I have to drum it in to you, or what? There's no way around it—multiplication tables are just one of those things that we, as teachers, have to drum in every day in math class.
Farlex Dictionary of Idioms. © 2024 Farlex, Inc, all rights reserved.