How can teachers, executives, and other public speakers make an interactive presentation to a large audience? Up until now, techniques for polling the audience relied on personal electronic devices, such as smart phones or special purpose “clickers”. To enable real-time polling of any audience, we introduce a new technique using computer vision. Each member of the audience is given a qCard: an ordinary sheet of paper with a printed barcode. The speaker asks a multiple-choice question, and audience members respond by holding their qCard in different ways. Using a laptop and digital camera, our software automatically recognizes and aggregates the responses. In this talk, we will describe our experience piloting this technology in Bangalore schools. We will also conduct a live demonstration!