This Teaching Resource provides lecture notes, slides, and a problem set for introducing graduate-level students to computational biology through a simple mathematical model of the cell cycle. The model simulates interactions between cyclin B and cyclin-dependent kinase 1, proteins that together form the mitosis-promoting factor (MPF), which initiates the processes leading to mitosis. The lecture begins with a biological background describing the importance of MPF for mitosis, the components of MPF, and the changes in cellular MPF observed during different phases of the cell cycle. The model is compared with newer, more mechanistically detailed models of the same process, which allows for a discussion of the insights that can be gained even from simplified models. The lecture concludes with a demonstration of how this model can be implemented in the scientific programming language MATLAB and includes a problem set.