Abstract: A demonstrative teaching apparatus for teaching the relationship between variable pictorial and/or graphic displays and their respective numerical values, in which the entire apparatus is positioned within an apparatus housing. The apparatus housing incorporates viewing areas on its front and rear sides so as to provide optical display of the relevant teaching portions of the apparatus. The front viewing area reveals the position of the segmented display while the rear viewing area reveals numerical indicia corresponding to the display of segments appearing through the first viewing area. The segmented display and, in turn, its respective numerical indicia, can be increased or decreased by forward or reverse rotation of a circular disk. The circular disk is precluded from excessive rotation in either direction through stopping mechanisms which limit the inadvertent winding or unwinding of the segmented display.