Learning about chromosomes is standard fare in biology classrooms today. However, students may find it difficult to understand the relationships among the "genome", "chromosomes", "genes", a "gene locus", and "alleles". In the simple activity described in this article, which follows the 5E approach (Bybee et al. 2006), students create paper models of chromosomes to learn how these terms are related and also to learn about the science and engineering practice of modeling. This activity should come after students have been taught DNA structure, including complementary base pairs (Adenine-Thymine; Guanine-Cytosine).