Polarization happens when people become divided into contrasting groups. If a teacher lets the class vote on whether to have class outside or not, and half wants to stay and the other half wants to go, that issue caused polarization.
Polarization is a concept that comes from science, and it involves light, radiation, or magnetism moving in specific directions. Outside science, polarization usually refers to how people think, especially when two views emerge that drive people apart, kind of like two opposing magnets. When Democrats and Republicans fight, it can cause polarization. A Civil War is a serious form of polarization. Polarization involves people moving in two directions — they're becoming almost as separate as the North and South Pole.