6A01  Speed of Light
6A02  Straight Line Propagation of Light
            .10 Light in a Vacuum
            .15 Straight Line Propagation
6A10  Reflection from Flat Surfaces
            .11 Angle of Incidence and Reflection
            .18 Microwave Reflection
            .20 Diffuse/Specular Reflection
            .30 Corner Reflector
            .37 Parity Reversal in a Mirror
            .40 Hinged Mirrors
            .45 Barbershop Mirrors
            .60 Location of Image
            .65 Mirror Box
6A20  Reflection from Curved Sufaces
            .10 Concave and Convex Mirrors
            .20 Spherical Aberration in a Mirror
            .31 Large Concave Mirror
            .60 Energy at a Focal Point
6A40  Refractive Index
            .30 Disappearing Eye Dropper
6A42  Refraction at Flat Surfaces
            .12 Refraction/Reflection from Plastic Block
            .43 Small Refraction Tank
            .47 Acrylic/Lead Glass Refraction
            .51 Three Different Prisms
6A44  Total Internal Reflection
            .20 Critical Angle/Total Internal Reflection
            .40 Light Pipes
            .41 Optical Path in Fibers
            .45 Laser Waterfall
            .55 Silver Soot Ball
6A46  Rainbow
            .30 Rainbow Disc
6A60  Thin Lens
            .20 Ray Tracing with Lenses
            .30 Real Image Formation
            .35 Lens Magnification
6A61  Pinhole
            .20 Pinhole Camera
6A65  Thick Lens
            .21 Chromatic Aberration
            .31 Off Axis Distortion
            .34 Astigmatism
            .40 Spherical Aberration
            .52 Fillable Air Lenses
            .70 Fresnel Lens
6A70  Optical Instruments