The real magic of interactive teaching is in your pedagogy - not in the tools you use. All the tools can do is make it easier, more efficient, & more effective. Obviously these are worthwhile things, or we would not have gone to the trouble of developing Classtalk. But, there is another alternative if you don't have the money for technology. Get started today with Flashcards! Eric Mazur describes them in his book "Peer Instruction", and Mani Manivannan of SE Louisiana Univ. had presented several papers on their use. Louis Abrahamson, one of the inventors of Classtalk, also used this technique at the University of Zimbabwe in June 1991. He describes his experience.
"I was teaching a software engineering course to about 80 second-year computer science students. Zimbabwean students tend to be very passive, so I wanted to engage them more than I could by just lecturing. At my father-in-law's house I got some white card and five old cans of different colored paint. I painted one side of the cards to make 35 packs of colored cards (about 8"x6" in size). An elastic band held each pack with five different colored cards together. At the start of my first class, I asked the students to form themselves into groups of 2 or 3, and for one person from each group to collect a pack of cards. Later in the course of my lectures, I would ask multiple-choice questions and color-code each option, give the class a fixed amount of time (1 to 3 mins) to discuss the answer among themselves in their group. At time-up one person in each group would hold up a card (with the colored side toward the front), and five volunteers in front row would stand-up, turn around and count a color. I drew the resulting histogram on the board, and would use it as a springboard for discussion, resolving conceptual differences, or simply for brief comments before moving on to the next topic. Of course, I had no permanent records so student commitment to their answers was not as high as in Classtalk classes, but the process was quick, smooth, effective, and very rewarding in terms of class involvement with the material. I would do it again in a flash!"