Master Ruler Video
In addition to the Master Ruler, this company offers other useful innovations like the Master Clock, Master Fractions, Master Angles and the Marvels of Measurement Poster.
I love math products that help me teach the concepts in a new and hands-on way. This one did just that. It also came with a handy Lesson book, and the kiddos are happily measuring everything in sight.
See what my other reviewers thought here