X1014307866-00349-80990</DOCNO> The Mathematics of Lenses Lesson 1: Refraction at a Boundary Boundary Behavior Refraction and Sight The Cause of Refraction Optical Density and Light Speed The Direction of Bending The Secret of the Archer Fish Lesson 2: The Mathematics of Refraction The Angle of Refraction Snell's Law Ray Tracing and Problem-Solving Determination of n Values Lesson 3: Total Internal Reflection Boundary Behavior Revisited Total Internal Reflection The Critical Angle Lesson 