Often coupled with digital whiteboard systems, student wireless response systems were also much in evidence at BETT. All but one of the ones I saw being used allowed multiple responses and not just two.
It is an interesting approach to try. It certainly could enhance certain lessons and, providing that it not every lesson is used in this way, would be involving and motivating. The demonstrations that I saw were a little laboured and not very slick, with the exhibition visitors not rushing to participate in this way!