This 1-page (double-sided) resource may be used while introducing the classifications within the real number system (irrational, rational, integer, whole, and natural numbers), as a practice page after introduction, or as a quiz. It includes a diagram to be filled with category names (from word bank) and numbers. It also includes matching number sets to names and definitions. Finally, it asks students to identify all sets in which a number belongs. Answer key is included.