RNA interference (abbreviated RNAi) is a relatively new discovery in the field of mechanisms that serve to regulate gene expression (a.k.a. protein synthesis). Gene expression can be regulated at the transcriptional level (mRNA production, processing, or stability) and at the translational level (protein synthesis). RNAi acts in a gene-specific manner and degrades the specific message (mRNA) to lower mRNA stability and, in the process, decreases protein production. The RNAi mechanism thus acts as a negative regulator of gene expression and undoubtedly has been one of the most significant developments in genetics and molecular biology in recent years. I present a teaching module that can help high school students experience this unique post-transcriptional regulatory mechanism.