Students can use seed characteristics to discriminate between the different kinds of legumes using taxonomic classification processes of sorting and ranking, followed by construction of taxonomic keys. The application of the Learning Cycle process to taxonomic principles, hierarchical classification, and construction of keys presents the components of classification that include sorting (grouping) and ranking as separate stages in classification. In addition, it separates production and use of keys from the classification process and presents it as a useful product of classification. Students frequently use keys to identify trees, insects, wildflowers, minerals, or rocks. Understanding concepts behind the classification process and production of taxonomic keys will enable the students to select appropriate keys for their region. This article describes activities in which this can be successfully achieved in the classroom.