Ducksters
Ducksters: Physics for Kids: Properties of Waves
Kids learn about the properties waves in the science of physics including amplitude, wavelength, frequency, period, and speed.
Other
University of Winnipeg: The Simple Pendulum
The periodic motion of a pendulum is described with words and equations; little conceptual emphasis. Sample problems with solutions are provided.
Mocomi & Anibrain Digital Technologies
Mocomi: What Is Sound?
Defines sound, how it travels, the components of a sound wave, the different types, and other fun facts.