An attractive MATLAB-based tool for teaching the basics of autocorrelation function and noise concepts is presented in this paper. This tool enhances traditional in-classroom lecturing. The demonstrations of the tool described here highlight the description of the autocorrelation function (ACF) in a general case for wide-sense stationary (WSS) processes, and for several important special processes including Gaussian white noise (GWN), non-Gaussian white noise, and Gaussian non-white noise. The demonstrations were designed for and introduced in the graduate-level course "Introduction to Communications," but would also be appropriate at the undergraduate level in various courses on signals or communications, or in a basic course on probability and random variables. The course description and program evaluations are also included. (Contains 14 figures and 1 table.)