  We propose a low-cost classroom response system requiring a single mobile
device for the teacher and cards with printed codes for the students. We aim at
broadening the adoption of active learning techniques in developing countries,
offering a tool for easy implementation. We embody the solution as a smartphone
application, describing the development history, pitfalls, and lessons learned
that might be helpful for other small academic teams. We also described the
results of the first round usability tests we performed on the first prototype,
and how the affected the current version of the software. A beta release
version is currently available for the public at large.
