I have a set of classroom response system handsets, aka "clickers". They interface with a receiver that plugs into a laptop via USB. The clickers require 2 AA batteries.
I used these for many years in my classes until I switched to wireless using the students' smartphones. Students loved them, and it allowed even the shyest student to respond to classroom questions. As a teacher, I had instant feedback as to whether or not students understood the lesson.
I hope someone can put these to good use.Fair Offer Policy applies