Back when I was teaching, we had several attempts to improve the learning and teaching experience using student handsets which communicate back to a central system. Within their limits, such trials were generally successful; enough that the college bought several sets.
However, I always felt that the system was was woefully underused. Using such handsets in an entirely teacher-driven way for such tasks as in-lesson progress quizzes is only a fraction of the story.
Why not use them as an anonymous and continuous “backchannel” to indicate a preference that the teacher speed up, slow down, go into more detail, back off, give a concrete example, etc.?
Why bother with tedious register-taking when students can just “log in” using a remote handset?
Why not offer opportunities for learners and staff to anonymously vote on where the lesson goes next or indicate personal goals for a lesson or group exercise?
These are just a few “top of my head” ideas; there must be many more out there but they never seem to make it into practice.