Yeah, naming is tough! If you're guiding people from something that resembles pranayama to eventually dhyana then I guess calling it meditation would be fine. I'd just make it clear to your students that working with the breath is a preliminary practice, to help them to begin to recognize awareness. And in particular not to attach to the high that comes with exercises like this, chasing sensation. That could set them back when they need to learn about samatha, because vipassana eventually requires it (see, for example, mahamudra teachings).