Teaching Resource
Introduction
Benjamin Franklin was a scientist and an inventor. As he got older, he noticed he needed glasses for reading and seeing things far away. Franklin solved this problem by inventing bifocals, which were glasses made with two different lenses, one for seeing things up close, and the other for seeing things far away.
Water acts just like corrective lenses made of plastic or glass. The water refracts or changes the direction of a light beam. A water lens is known as a convex lens because it curves out in the middle....