Steve Draper of Glasgow University provides a good overview and a set of good resource links for
Electronic Voting Systems and interactive lectures.
He has very good short and long overviews of the teaching and leanring benefits of this suite of learning technologies and methods.
This is part of the Interactive lectures interest group (ILIG): main website index page. This site has a stunning wealth of information, include methods, research links, usage information,… on designing for interactivity in lectures…
Well worth a lengthy peruse…