polyhedra is in the shape of a regular polyhedra having a number of faces having geometric shapes the faces may be identical the number of faces can be changed depending on the demonstration preferably at least half of the faces of polyhedra 10 are blank i e they have no markings of any kind the remaining faces are marked with various indicia as desired for example the polyhedra 10 in the figures is constructed and arranged to emulate a die used to demonstrate probability a regular die is a cube having six square surface each surface having from one to six dots in the figures for the sake of clarity the faces and dots which are visible directly are shown in heavy lines while the faces and dots which are visible through the polyhedra are shown with light lines these six surfaces are represented on polyhedra 10 by six pentagonal faces 12 14 16 18 20 22 face 12 has one dot 11 the other faces have two three four five and six dots respectively the remaining faces 24 26 28 30 32 and 34 are blank importantly each face with an indicia is disposed opposite i e it is in parallel with a blank face for example face 12 is opposed to face 24 face 14 is opposed to face 26 and so on in the figures all the faces with indicia are clustered together or adjacent to.