You may be too grown up to get a ruler for back to school, but don't count the measuring tool out this fall. Jewelry line Digby + Iona chose the ruler as inspiration for their "Means of Measurement" collection, in which many of the pieces are engraved with a classic Galileo quote: "Measure what is measurable, make measurable what is not." 
The sterling silver Slide Caliper Necklace ($220) is a miniature and fully functioning ruler with a movable slide.
The Ruler Ring ($150)
Make Measurable Pendant ($170)