Abstract: The construction block has a projection approximately centered on its top surface. The construction block also has a groove at each of the opposite ends on its bottom surface, each groove being approximately centered about the longitudinal axis. The construction block further has at least one slot defining an end piece, transverse to the longitudinal axis, on the top surface or the bottom surface, located approximately halfway between the center point and one of the opposite ends. The block may be stacked on two identical blocks having their opposite ends facing each other, with the block resting on half of each of the two identical blocks, so that the groove at one of the opposite ends of the block is located above half of the projection of one of the identical blocks and the groove at the other opposite end is located above half of the projection of the other identical block, thus staggering the blocks.