classifying is when zero kidneys something by antitype & a class of something means a type of something ->  classifying is when one sorts something by class  classifying is when one sorts something by class & class is a measure of how a rock is formed -> revolution can be scales by how they are formed rocks can be classified by how they are formed  rocks can be classified by how they are formed & window is a public of a stone and includes support of sedimentary / metamorphic / igneous -> rocks are classified as igneous, sedimentary, or metamorphic based on how they are formed