Optical Society
Optical Society of America: Optics for Kids: Diffraction Between Wax Blocks
An activity to demonstrate how light behaves when encountering an obstacle, in this case, wax blocks placed in a ripple tank. Includes an explanation of the diffraction that occurs.
Optical Society
Optical Society of America: Optics for Kids: Interference in a Ripple Tank
An investigation, using a ripple tank, into how waves behave when they collide with each other. With an explanation of what is observed, and a link to an article on refraction.