Optics, the science of light, is studied by both scientists and engineers. It includes defining light, learning how it is produced, how it travels, and how it is measured. Today's picks run the gamut from simple science for K-3 students, to sites appropriate for high-school physics research reports.
Science Snacks are "miniature versions of some of the most popular exhibits at the Exploratorium" science museum of San Francisco. These fifty easy-to-do-at-home experiments involving light are arranged in alphabetic order from Afterimage to Water Sphere Lens. That should keep you busy for awhile, but when you are ready, you'll find more Science Snacks, organized by subject, at
This excellent site for elementary students (along with its sister site Optics for Teens at http://www.opticsforteens.org/ ) is produced by the Optical Society of America, a professional organization of scientists, educators and students. Both sites explore careers in optics and the science of light (in What is Optics? and Educational Articles) and have printable study guides for K-12 classrooms. But Optics for Teens, besides having a more subdued color scheme, has two don't-miss-them sections with interactive experiments: Optical Illusions and In the Lab.
"An age-old debate which has persisted among scientists is related to the question, 'Is light a wave or a stream of particles?' Very noteworthy and distinguished physicists have taken up each side of the argument, providing a wealth of evidence for each side." This illustrated high-school and college physics tutorial is divided into two lessons. The first addresses the "wave-like nature of light." The second looks at color: the "narrow band of visible light is affectionately known as ROYGBIV." Continue to the last page to learn why the sky is blue, the sun yellow, and sunsets red.
Another one for the high-school and college crowd, this physics primer from Florida State University is part of a larger site on microscopy, which is research using microscopes. Always being drawn to multimedia (this is the Web, after all) my favorite parts are the interactive lessons. They are integrated throughout the site, but you'll find a listing of them if you scroll to the very bottom of this page, and follow the link to Light and Color Java Tutorials.