This three-module curriculum was prepared by the Office of Biotechnology at Iowa State University and published by ISU Extension for high school teachers or extension educators to use with grades 9-12 or adult audiences. In the 1860’s, Gregoire Mendel conducted plant breeding experiments on the common garden pea that led to the first theories about the units of inheritance that we call genes. Mendel’s work provided the foundation for today’s molecular marker technologies. Molecular markers are pieces of DNA that are linked to or are part of a gene associated with a desirable characteristic, such as seed size or disease resistance. Through a process called marker assisted selection, scientists can use molecular markers to select plants or animals that have the characteristic without waiting for them to grow to maturity. The new curriculum uses hands-on activities to trace the development of modern molecular genetics and bioethics issues from Mendel’s experiments to current marker assisted selection of plant and animals. Each module is designed to be used independently or with the other modules. For educators, each module contains background information, lesson plans, Internet resources, and overhead transparency masters. Informational and activity handouts that can be photocopied for students are included.