Explore ray tracing using Microsoft Excel. The linked spreadsheet traces rays across a single spherical lens in the paraxial approximation using matrix multiplication. It contains a macro, which increments the launch angle for 7 rays. The results of the calculations are plotted. The object position, the radii of the lens and the indexes of refraction of the lens and the surrounding material can be chosen by the user. Please explore the spreadsheet and feel free to modify it.