This lesson blends physics, geometric optics, and biology as students explore light refraction through convex and concave "lenses" made of clear gelatin. The activity promotes understanding of four key concepts: 1) convex lenses cause light to converge, while concave cause divergence; 2) Focal length can be determined from the convergence point of a convex lens; 3) Ray diagrams provide a geometric way to depict the path of light through a transparent object; and 4) The malleable gelatin lenses can model the function of the human eye.

This AAPT Lesson Plan was inspired by two articles in The Physics Teacher magazine: "Edible Optics: Using Gelatin to Demonstrate Properties of Light" by Patrick Bunton, and "Construction of Optical Elements with Gelatin" by Mario Branca and Isabella Soletta.