Each year, in thousands of classrooms across the country, students classify animals, rocks, and other things as part of their science studies. Each year, thousands of students no doubt ask, “Why in the heck are we doing this?” Classifying things according to their properties and characteristics is a big part of science, but what’s the purpose? Why do it in science class, and why do scientists do it as part of their work? Discover the answers to these questions in this month’s column.