Elementary teachers of science are at a great advantage because observation--collecting information about the world using the five senses--and classification--sorting things by properties--come so naturally to children. Many examples of classification occur in science: Scientists, for example, group things starting with large categories, such as living or nonliving, and then further classify them into more distinct groups based on specific properties. Buttons are ideal objects when teaching children about properties and classification. These familiar and inexpensive objects provide a meaningful teaching tool in the classroom. This article presents a lesson using buttons and premade Venn diagram mats. This lesson can be presented either as a basic introduction to classification by properties, or it can be used to offer increasingly complex explorations that help students experience a more in-depth understanding of properties. The lesson can easily be adapted for use with children at any cognitive and developmental level or grade. (Contains 1 resource.)