US Patent 7415772 Rainbow ruler

A set of rulers for teaching the concept of measurements includes a first ruler having a first group of incremental division lines corresponding to a first group of measured lengths, each line of the first group having a first length and a first color. A second ruler in the set adds a second group of incremental division lines corresponding to a second group of measured lengths, each line of the second group having a second length and a second color, the second group of lines extending from an distal end portion of the first group where the second group of measured lengths corresponds to the first group. A third ruler of the set adds a third group of incremental lines corresponding to a third group of measured lengths, each line of the third group having a third length and color and, where the third group of measured lengths corresponds to the first and second groups, extends from the distal ends of the second group of lines. A method of using the set of rulers to teach is also disclosed.