Cyclic driving happens all around us. Buildings and bridges are repeatedly loaded and unloaded, and many organisms synchronize their functions with day and night. This kind of driving can change a material, and in some cases it forms memories that can be recalled later. I present two examples of materials that, when deformed repeatedly, can "learn" and report the magnitudes of those deformations: a suspension of particles in liquid, and an amorphous solid made of closely packed particles. These materials exemplify two different but generic ways that non-equilibrium systems can retain memories, with suspensions sharing their behavior with charge-density wave conductors, and amorphous solids approximating the return-point behavior best known in magnetic materials. Studying memory formation can illuminate a material’s non-equilibrium nature, including the benefits of disorder and noise for encoding information