In this article we present simple and low-cost experiments about the polarization of light. We use an LCD monitor or an RGB LED light bulb with a Polaroid as a source of polarized radiation, a polarizer sheet as an analyzer, and a smartphone camera to measure light intensities. Thus, using a digital camera to acquire videos students can explore in a quantitative manner the polarization of light by measuring the typical features of Malus' law. Both for the topic and the simplicity of the activities, this experiment is suitable for undergraduates.