Abstract: An educational interlocking block set having six facing sides. Two of the opposite block sides have either a four spaced projecting male protrusions or a four spaced complimentarily shaped receiving female recesses for male protrusions of an adjoining interconnected block. The other four sides of each block may have the same letter thereon to permit the viewing of their displayed surfaces. When several interlocked blocks are viewed, either in horizontal or vertical configurations, words may be spelled out by the displayed letters of the blocks. Vertically aligned blocks may be either stacked upon joined lower horizontally disposed blocks or may be joined vertically thereto. An almost endless configuration of joined blocks representing different joined shapes, such as pyramids and diamonds, may be constructed with visible surface letters.