Exploratorium
Exploratorium: Critical Angle
Students can see light reflected and refracted in this demonstration. They will also discover the total internal reflection of light.
Other
Ntnu Virtual Physics Lab: Thick Lens Java Applet
An interactive Java applet which allows the user to investigate the path of light through a lens shape object. The shape of the object, the index of refraction of the material, and the location of the incident rays can be altered.
CK-12 Foundation
Ck 12: Physical Science: Refraction of Light
[Free Registration/Login may be required to access all resource tools.] Discusses refraction of light in matter and how light changes its speed and angle of refraction according to the type of medium it is travelling through.
Georgia State University
Georgia State University: Hyper Physics: Reflection and Refraction
Reflection and refraction are explained with an experiment that uses a sheet of paper, cardboard, and other common materials.
Walter Fendt
Walter Fendt: Reflection and Refraction of Light
Defines the refraction of light and provides an applet for investigating it.
University of St. Andrews (UK)
University of St. Andrews: Willebrord Snell
A fairly short biographical sketch of Willebrord Snell (1591-1626 CE). Discusses his upbringing, education and professional life.