The "Central Dogma" of genetics states that one gene, located in a DNA molecule, is ultimately translated into one protein. As important as this idea is, many teachers shy away from teaching the actual mechanism of gene translation, and many students find the concepts abstract and inaccessible. This article describes a unit, called Genetics Building Blocks, that models these concepts in a visual and concrete way. The activity uses colored plastic building blocks to help students gain understanding of protein synthesis. Protein synthesis is the elegant process by which DNA directs the production of proteins and, hence, the production of enzymes that control the expression of traits in living organisms. The use of plastic building blocks becomes particularly effective because students observe variation in the different color schemes. The activity has achieved a high degree of success with over 500 ninth- and tenth-grade students at a large urban high school. Genetics Building Blocks is a unit that, when given enough time to develop, involves students in their own learning in an enthusiastic manner. (Contains 6 figures.)