The 1:100 scale works as a centimeters ruler while the 1-inch scale can be your regular inches ruler. But that’s not all.

Create your own centimeter ruler. Then, estimate and measure with lengths with it. Warm up with a Mystery Math Mistake as you add two 2-digit numbers using a decomposition strategy. Think through ...

“ONE 3 scale ruler offers two editions, the metric and the imperial systems, and with a simple side-flipping, you can easily gain access to different scales.

It’s the attention to detail that often differentiates a good product from a great product, but designer Norihiko Terayama goes above and beyond the call of duty with his f,l,o,w,e,r,s ruler ...