Abstract: A four-pan algebra balance includes an imbalance correction mechanism for maintaining a balance beam in a horizontal equilibrium position unless the imbalance between the two sides of the device exceeds a predetermined amount. The balance includes a base, an upright stand mounted to, and extending substantially vertically from the base, a crossbar mounted to an upper end of the stand so as to extend substantially horizontally and the balance beam pivotally coupled to a midpoint of the stand. A first weight receptacle subassembly including two pans is coupled to a first end of the crossbar and a first end of the balance beam and a second weight receptacle subassembly including two pans is coupled to a second end of the crossbar and a second end of the balance beam. A visual indicator provides an indication of the relative equality of the first and second weight receptacle subassemblies.

Abstract: A polyhedra for emulating an object or other phenomena with marked surfaces, includes a plurality of faces, some with markings and some being blank. The surfaces are arranged about the polyhedra so that each marked face is opposite a blank face. The polyhedra may be used for conducting and/or demonstrating the principles of probability in conjunction with a projection device.

Abstract: A method is provided for teaching and learning multiplication wherein unit power of ten values are assigned to strips of transparent material. The strips are positioned on a multiplication table array over the rows and columns representing the digits of the numbers to be multiplied. The color of the strip determines the unit value of the digits. By multiplying the value of each array element on that intersection of two strips by the unit value of the composite color formed by the overlying of the two strips and summing the products of the digit values and the unit values the final value of the numbers to be multiplied is obtained.