Optical polarization phenomena are omnipresent in physics, chemistry, biology, and technology. Studying optical polarization is best done through an interdisciplinary approach that combines biology and technology, which usually makes things more interesting to students. Seeing Haidinger's brush for the first time can be an exciting discovery for many students. Polarization also has profound conceptual relevance to school curricula, and many beautiful polarization experiments can be performed with cheap materials. In this article we present experiments that students can perform with a smartphone as a source of polarized light and the naked eye as their analyzer.