in the drawings or other more curvilinear shapes by properly sizing and locating the shingle locating features such that the mating features of overlapping shingles interfit with one another as a new course of shingles is laid over an existing course the shingles are properly aligned such that the slots 18 19 alternate as shown in layout 80 fig6 the relative shingle locations are shown in more detail in layout 90 fig7 with overlaid vertical axes illustrating the relative locations of shingles 30 a and 30 b also shown in fig7 is another advantage in which starter strip 44 can be laid down at the bottom edge of the roof strip 44 can have a width that is about the same as the width of shingle 30 a from its bottom edge up to the bottom of the locating strip that is added to the back of the shingle in this case the starter strip fills in the space between this portion of the back of the shingle and the roof thus presenting a flat surface to the roof this strip would typically be about 7 inches high so that the underlayment is not exposed beneath the slots of the first course of shingles when they are laid over this starter strip as an alternative regular straight edge shingles can be used instead of this special starter strip as is typically done today the invention accomplishes interlocked shingles that are level and plumb across both the width and height of the roof thereby substantially facilitating installment and also creating a better looking end result in order to accomplish this result the shingles should have at least two spaced locating features proximate their top edge.