Blackboard optics: Light source and lucite prism.

Blackboard optics: Light source and Lucite prism (and mirrors and lenses). The Blackboard Optics Kit contains triangular and rectangular Lucite prisms (as well as a semicircular disk, converging and diverging lenses, and plane, concave and convex mirrors.) A light source emits a collimated ray of white light that reflects from and refracts through the prism, as well as grazing the chalkboard so that the class can see. The light has a magnetic base which sticks to the steel-backed chalkboards. The prisms (and lenses, etc.) are held against the blackboard by a strip of Plexiglas with magnets at both ends. The light source can be arranged to demonstrate refraction, reflection, internal reflection, and critical angle, etc.