Bacterial transformation is a commonly used technique in genetic engineering that involves transferring a gene of interest into a bacterial host so that the bacteria can be used to produce large quantities of the gene product. Although several kits are available for performing bacterial transformation in the classroom, students do not always clearly understand what they are doing by following the procedure. This document presents an exercise that uses paper DNA sequences to simulate the process of bacterial transformation and can be used in biochemistry, biotechnology, or any level biology class. In advanced biology classes it can be used to provide an introduction to the bacterial transformation laboratory while in general biology classes it can be used to help students understand this new technology. In the exercise students identify a gene of interest, choose a restriction enzyme to isolate the gene, construct a plasmid vector to carry the gene into bacterial cells, ligate the gene into the plasmid, then transcribe and translate the gene product. Key concepts include DNA structure and function, restriction enzymes, plasmid vectors, one gene-one polypeptide, transcription, and translation. (JRH)