Optical Society
Optical Society of America: Optics for Kids: Lenses and Geometrical Optics
Article explaining what lenses are and how they work. At the end of the article, there are links to several hands-on activities for investigating lenses.
Optical Society
Optical Society of America: Optics for Kids: Mirrors & the Law of Reflection
A simple activity to investigate how light reflects off a flat surface, a convex one, and a concave one. With a link to an article on reflection.