Abstract: A probability demonstrator has a transparent housing having a bead reservoir at the top of the housing, a plurality of pegs disposed in a triangular matrix configuration in a mid-portion of the housing, and a plurality of parallel bead bins disposed at a bottom portion of the housing. Spherical beads are enclosed within the housing. The spherical beads are loaded into the bead reservoir by rotating the housing on its central pivots. When rotated again, the spherical beads cascade through the triangular matrix and come to rest within the plurality of bead bins. The probability demonstrator is configured to allow bead flow through the device without hanging up through any part of the device until the spherical beads come to rest within the bead bins, resulting in a histogram showing a normal distribution. A single larger diameter spherical bead may be included with the plurality of spherical beads to demonstrate a single random outcome.

Abstract: A defrost or thaw measuring device has a dumbbell or hourglass-shaped rotatable compartment with a cavity, the cavity being partly filled with at least two phase change materials having different melting points. The measuring device may determine the time period of thawing at two or more temperature intervals in the refrigeration space.