You cooked the perfect turkey last Thanksgiving. This year, you want it to be just as good, but the turkey you got is twice as heavy! How much longer should you cook it for, given the time it took to cook the smaller turkey last year? Protip: take this class to find out! Diffusion is an intuitive phenomenon: in the absence of additional forces, stuff tends to move from where there is an abundance of it, to where there is a scarcity of it. Whether it concerns chemical species, thermal energy, or stock prices, diffusion underlies the understanding of innumerable science and engineering systems. It is a particularly deep insight that diffusion arises purely from the stochastic motions of microscopic particles, which we can model mathematically using the random walk. We will use Microsoft Excel to investigate how a random walk can result in macroscopic diffusive spreading. Scientists and engineers describe diffusion with Partial Differential Equations (PDEs), but we can already understand its important characteristics just using elementary algebra. In particular, we will discuss the “scaling” of diffusion processes: how does the time for diffusion depend on the dimensions of the physical domain of interest (e.g., this year’s turkey)?