This lab focuses on predictable design. Students will examine the role of parts, such as promoters and ribosome binding sites, in determining the output of a genetic device. The students measure b-galactosidase enzymatic activity as the device’s output, enabling them to look through the lens of molecular genetics to evaluate a device’s behavior. Students study transcription, translation, the lac operon and enzyme function within a synthetic biology context. Part 1 of the lab offers an opportunity for the students to develop microbiology skills, though this procedure may be done by the teacher if time is an issue. In Part 2, the students lyse the cells to release the β-galactosidase enzyme and then carry out a timed enzymatic reaction, later calculating the enzyme activity associated with each genetic construct.