With trick-or-treaters still categorizing Halloween candy, it is a good time to introduce students to Carl Linnaeus. He liked putting things into categories too – especially plants and animals. In the wonderful children’s book, The Right Word: Roget and his Thesaurus, Jen Bryant describes Carl Linnaeus as a man who “put the names of animals and plants in categories, and that made nature much easier to study.” His classification system has seven levels, and each animal on the planet can...