Dr. Marina Milner-Bolotin was featured in The Ubyssey recently, and discussed the use of “clickers” in the classroom.
From the September 12, 2012 article by Coral Kasirer:
Before the age of clickers, Milner-Bolotin recalls students raising coloured cards to signal their answer to a multiple choice question asked in class. These ABC or colour cards, as well as the rudimentary clicker technology, were plagued by technical difficulties, which led to them eventually being phased out.
Read more here.