Patent Document ID: 4129960
Application ID: 05694170
Patent Flag: 1

Claim One:
1. Interlocking educational and recreational hollow blocks each comprising a three-dimensional right rectangular structure having: (A) four vertical side walls each having a planar face sharing common edges with two others, (B) a horizontal top wall having a planar face sharing a common edge with each of said side wall faces, (C) a flat bottom surface sharing a common edge with each of said side wall faces, said bottom surface defining an open face of said hollow block, said bottom surface further comprising the edges of intersecting diagonal ribs extending verticaly down from said top wall within said hollow block, (D) a plurality of male interlock members on said ribs projecting perpendicularly therefrom, one member adjacent each of the corners thereof, each of said members being spaced equidistantly inwardly from the adjacent pair of edges, and (E) a plurality of female interlock members engageable with the male members of an abutting block and recessed into each of the remaining wall faces, one member adjacent each of the corners thereof, each of said female interlock members being spaced equidistantly inwardly from the edges of the faces by the same distance said male interlock members are spaced inwardly from the edges and being of a depth sufficient to receive the length of a male member.