University of California
Center Science Edu.: Electromagnetic Radiation on Trial
Here is a 1-5 day unit on electromagnetic radiation that features a teacher guide and student activities with extensions.
Synopsys
Synopsys: Optics: A Gentle Intro to Optical Design: Wave Particle Duality
Discusses the manner in which light behaves as both wave and particle. This dualistic nature of light is one topic of many on the page.
Science Struck
Science Struck: Wavelength of Visible Light Spectrum
Explains where visible light fits into the electromagnetic spectrum and the wavelengths for the different colors we see.
California State University
Electronic Homework: Wavelength, Frequency and Energy
Users solve computational problems concerning the wavelength, frequency, and energy relationships. Fill in the missing values and submit your answers to be corrected.